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SEYMOUR  DURST 


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NEW  YORK  WATER  SUPPLY. 


DEPARTMENT  OF  PUBLIC  WORKS. 


REPORT 

OF 

HUBERT  0.  THOMPSON,  Commissioner  of  Public  Works, 

TO  THE 

HONORABLE  WM.  R.  GRACE, 

MAYOR   OF   THE   CITY   OF   NEW  YORK, 

ON 

Proposed  New  Aqueduct  and  Storage  Reservoir  for 
Additional  Supply  from  Croton  River, 

WITH  DETAILED  REPORT  OF 

ISAAC  NEWTON, 

CHIEF      ENGINEER      OF      THE     CROTON  AQUEDUCT, 

AND 

OPINIONS  OF  CONSULTING  ENGINEERS. 

NEW  YORK,  FEBRUARY,  1882. 


115 
.MS 

A4 


Digitized  by  the  Internet  Archive 
in  2013 


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Compliments  of 

Hubert  O.  Thompson. 
Com'r  Public  Works 

DEPARTMENT  OF  PUBLIC  WORKS. 


Department  of  Public  Works, 
Commissioner's  Office,  No.  31  Chambers  Street, 

New  YORK,  February  23,  1882. 

Hon.  William  R.  Grace,  Mayor : 

SIR — In  the  quarterly  and  annual  report  which  I  transmitted  to 
you  on  the  13th  instant,  I  stated  that  under  the  direction  of  Mr.  Isaac 
Newton,  Chief-Engineer  of  the  Croton  aqueduct,  with  the  assistance 
of  Mr.  E.  S.  Chesbrough,  as  Consulting  Engineer,  careful  investiga- 
tions and  surveys  have  been  made  during  the  past  yeai,  to  ascertain 
the  best  method  of  securing  an  additional  water  supply  for  the  city  ; 
that  these  investigations  and  surveys  have  led  to  a  definite  plan  for  a 
new  aqueduct  from  the  Croton  river  to  the  city,  the  outlines  of  which 
I  briefly  stated  ;  that  upon  examination  the  plan  has  received  the 
approval  of  Mr.  John  B.  Jervis,  the  distinguished  constructor  of  the 
Croton  aqueduct,  Mr.  James  B.  Francis,  President  of  the  American 
Society  of  Civil  Engineers,  and  that  it  was  also  examined  and 
approved  by  Mr.  Robert  K.  Martin,  under  whose  direction  a  similar 
work,  the  Baltimore  water-works  tunnel,  was  recently  successfully 
constructed.  I  have  now  the  honor  of  transmitting  to  you  Chief- 
Engineer  Newton's  report  of  the  proposed  plan,  with  the  opinions 
and  approval  of  the  eminent  engineers  who  have  examined  it  in  all 
its  various  features. 

The  facts  and  circumstances  which  have  led  to  the  immediate 
necessity  of  another  aqueduct  or  conduit  to  bring  a  large  additional 
supply  of  water  to  the  city  have  been  so  often  stated  in  previous 
reports  of  this  Department,  and  they  are  so  fully  understood  and 
appreciated  by  you,  and  I  believe  by  the  greater  part  of  the  people 
of  this  city,  that  they  need  no  repetition  here. 

The  only  questions  which  remain  open  for  discussion  are,  as  to 
the  source  from  which  the  supply  should  be  obtained,  and  the  means 
of  collecting  it  and  conveying  it  to  the  city. 


iv 


I  believe  there  is  no  difference  of  opinion  among  engineers  and 
others  who  have  given  the  subject  attention  and  study,  that  in  regard 
to  geographical  position,  quality  of  water,  and  facility  of  means  for 
conducting  the  water  to  the  city,  the  Croton  river  and  water-shed  is 
the  most  desirable  source  of  supply. 

The  only  consideration  which  has  led  to  the  suggestion  of  other 
sources,  is  a  supposition  that  the  Croton  water-shed  cannot  be  relied 
upon  to  furnish  enough  water  at  all  times  for  a  new  aqueduct  of  the 
required  capacity. 

Let  it  be  shown  that  this  supposition  or  fear  is  groundless,  and 
there  can  be  no  hesitation  in  rejecting,  for  very  obvious  and  potent 
reasons,  the  propositions  of  obtaining  pure  fresh  water  from  the  upper 
Hudson  river,  from  Lakes  George,  Erie,  Ontario,  or  Champlain,  from 
the  Passaic  or  Hackensack  rivers  in  New  Jersey,  from  the  Housatonic 
river  in  Massachusetts,  or  Connecticut,  or  from  the  streams  in  Rock- 
land and  Orange  counties. 

The  project  of  using  the  salt  water  which  surrounds  the  city,  as  an 
auxiliary  to  the  city's  water  supply,  continues  to  be  brought  forward 
from  time  to  time,  by  persons  who  have  evidently  not  given  the  sub- 
ject sufficient  consideration.  The  objections  to  it  are  so  apparent  and 
conclusive,  that  engineers  do  not  consider  it  worthy  of  serious  con- 
sideration. 

In  view  of  the  many  questions,  however,  which  are  put  to  me  by 
citizens,  why  we  do  not  propose  or  make  preparations  to  use  salt 
water,  I  will  briefly  state  the  objections  to  it. 

We  have  now  512  miles  of  iron  pipes,  with  5,427  stop-cocks,  and 
6,496  fire-hydrants,  to  distribute  the  Croton  water  in  the  streets  of  the 
city.  To  make  the  salt  water  of  real  service  for  the  very  limited 
purposes  for  which  it  can  be  used,  it  would  be  necessary  to  duplicate 
the  greatest  part  of  the  distributing  system,  and  to  erect  and  maintain 
pumping  machinery  and  stand  pipes,  at  a  total  cost  of  probably  not 
less  than  twelve  to  fifteen  million  dollars.  Considering  that  less  than 
five  per  cent,  of  the  present  water  supply  is  used  for  extinguishing 
fires  and  for  cleaning  streets,  the  principal  or  almost  exclusive  uses  to 
which  salt  water  can  be  put,  the  cost  of  a  salt-water  system,  as  com- 
pared with  any  of  the  new  projects  for  an  additional  fresh-water 
supply  of  ample  proportions,  is  so  enormous  as  to  place  it  out  of  the 


V 


question  on  that  ground  alone.    But  there  are  other  serious  objections 


to  it.  The  fire  underwriters  say  that  salt  water  used  in  extinguishing 
fires  would  be  likely  to  do  as  much  damage  to  merchandise  as  the 
flames  themselves.  The  rapid  corrosion  of  iron  pipes  along  the  river- 
front, where  they  come  in  contact  with  salt  water,  shows  that  it 
would  soon  corrode  the  mains,  stop-cocks,  and  hydrants,  and,  in  the 
opinion  of  the  Chief  of  the  Fire  Department,  wear  out  the  steam  fire 
engines.  For  use  on  the  streets  it  is  so  objectionable  in  a  sanitary 
point  of  view,  that  several  years  ago  the  Board  of  Health  prohibited 
and  forbade  street  sprinkling  with  salt  water. 

An  additional  fresh-water  supply  will  not  only  accomplish  all  that 
can  be  attained  by  utilizing  salt  water,  but  will  meet  the  many  other 
equally  important  objects  of  an  adequate  water  system,  for  which 
salt  water  would  be  useless.  The  salt-water  plan  may,  therefore,  be 
dismissed  without  further  reference. 

The  supposition  or  fear  entertained  by  many  that  the  Croton 
water-shed  is  not  capable  of  furnishing  a  constant  supply  for  a  new 
and  large  aqueduct,  shows  an  imperfect  knowledge  or  misconception 
of  the  facts.  Accurate  observations  and  measurements  of  the  rain-fall 
and  of  the  quantity  of  water  running  over  the  Croton  dam  for  the 
past  sixteen  years,  prove  that  in  the  driest  of  these  years,  1880,  the 
average  daily  flow  of  the  Croton  river  was  250,000,000  gallons.  All 
that  is  needed  to  secure  that  supply  everyday  in  the  year  is  sufficient 
storage  capacity. 

The  capacity  of  the  Croton  water-shed  to  furnish  a  mininum  sup- 
ply of  250,000,000  gallons  per  day  being  proven,  the  whole  question 
is  narrowed  down  to  the  selection  of  the  plans  and  means  to  secure 
sufficient  storage  and  to  conduct  the  water  to  the  city. 

Chief-Engineer  Newton's  plan  covers  both  the  subject  of  storage, 
and  that  of  a  conduit  from  the  Croton  river  to  the  city.  In  regard  to 
storage  it  combines  in  the  highest  degree  the  merits  of  simplicity, 
efficiency  and  economy.  Instead  of  constructing  a  number  of 
smaller  reservoirs  on  the  slopes  of  the  Croton  water-shed,  on  sites 
established  by  surveys  made  under  the  direction  of  the  Croton  Aque- 
duct Board  in  1857-58,  it  is  proposed  to  build  a  dam  on  the  Croton 
river  at  Quaker  Bridge,  about  4.^4  miles  below  the  present  dam,  and 
5  miles  above  the  mouth  of  the  river,  forming  a  reservoir  of  3,635 


f  l&  J. 


vi 

acres  in  area,  with  a  storage  capacity  of  about  32,000,000,000  gallons 
above  the  level  of  the  proposed  new  aqueduct. 

The  advantages  of  this  single  reservoir  as  compared  with  a  num- 
ber of  smaller  ones  in  the  upper  portion  of  the  water-shed  are  : 

1st.  It  will  receive  the  entire  drainage  of  the  361  square  miles  of 
water-shed,  including  about  23  square  miles  below  Croton  lake,  not 
included  in  any  previous  reports,  plans,  or  calculations  ;  on  the  other 
hand,  the  combined  drainage  area  of  a  sufficient  number  of  smaller 
reservoirs  on  the  sites  heretofore  selected,  to  contain  32,000,000,000 
gallons  available  water,  would  be  less  than  200  square  miles.  Conse- 
quently the  large  reservoir  would  fill  much  more  rapidly  than  the 
smaller  ones. 

2d.  The  estimated  cost  of  building  this  reservoir  is  $4,000,000 
being  at  the  rate  of  $125  per  one  million  gallons  capacity. 

The  cost  of  building  the  smaller  reservoirs  was  estimated  by  my 
predecessor,  the  Hon.  Allan  Campbell,  in  his  report  of  August  12, 
1879,  at  $200  per  1,000,000  gallons  or  $6,400,000  for  a  storage 
capacity  equal  to  the  large  reservoir. 

3d.  Purity  of  water  is  better  secured  by  large  reservoirs  than  by 
smaller  ones. 

4th.  By  taking  the  proposed  site  the  length  of  aqueduct  required 
to  convey  the  water  to  the  city  is  shortened  about  ten  miles,  as  com- 
pared with  the  plans  proposed  in  1875. 

Though  the  dam  is  to  be  of  unusual  height,  and  will  have  to  resist 
the  weight  of  a  very  large  body  of  water,  the  eminent  and  experi- 
enced engineers  who  have  examined  the  entire  plan  pronounce  it 
entirely  practicable,  as  well  as  the  best  that  can  be  adopted.  Dams 
of  nearly  the  same  height  have  been  successfully  built  and  used  in 
France  and  elsewhere. 

The  conduit  from  the  dam  at  Quaker  Bridge  to  the  Harlem  river  at 
High  Bridge,  is  to  be  a  masonry  aqueduct,  circular  in  shape,  twelve 
feet  in  diameter,  and  capable  of  delivering  about  250,000,000  gallons 
of  water  per  day.  The  Harlem  river  and  Manhattan  valley  are  to  be 
crossed  by  syphons,  and  the  remainder  of  the  conduit  between  the 
Harlem  river  and  the  Central  Park  reservoir  is  to  be  in  tunnel  wher- 
ever possible.    The  distance  from  Quaker  Bridge  to  the  Harlem 


i  i 

Vll 


river,  on  the  line  selected,  is  26^4  miles,  only  9-100  mile  greater  than 
an  air  line  ;  it  is  ten  miles  shorter  than  the  Sawmill  river  line,  and  g*4 
miles  shorter  than  the  Bronx  river  line  surveyed  in  1875  under  the 
direction  of  General  Fitz  John  Porter.  It  has  the  further  most  valuable 
advantage  of  being  almost  wholly  in  rock  tunnel,  thus  securing  the 
greatest  possible  strength  and  stability  of  the  structure,  with  the  least 
cost  for  supervision  and  maintenance  after  it  is  completed. 

The  prominent  features  of  the  entire  plan  are  : 

1st.  Large  capacity  and  facility  for  collecting  and  storing 
zvater.  The  new  reservoir  will  receive  the  entire  drainage  of  the 
Croton  water-shed,  and  hold  32,000,000,000  gallons  of  water  above 
the  level  of  the  aqueduct,  and  can  therefore  supply  200,000,000  per 
day  for  160  days  without  recourse  to  the  flow  of  the  river.  With  the 
9,000,000,000  gallons  of  water  in  existing  storage  reservoirs  and  lakes, 
and  5,000,000,000  gallons  in  the  new  reservoir  about  to  be  built  on 
the  east  branch  of  the  Croton,  the  total  available  storage  capacity  will 
be  46,000,000,000  gallons,  sufficient  to  supply  200,000,000  gallons 
per  day  for  230  days. 

2d.  Large  capacity  and  utmost  at  tamable  strength  and  security  of  the 
conduit  to  convey  the  water  to  the  city.  The  new  aqueduct  will  be 
capable  of  delivering  250,000,000  gallons  per  day,  the  entire  minimum 
drainage  of  the  Croton  water-sheds.  This  will  supply  a  population  of 
2,500,000  at  the  rate  of  100  gallons  daily  per  capita,  or  3,300,000  at 
the  present  rate  of  consumption  (about  75  gallons  daily  per  capita). 
Add  to  it  the  capacity  of  the  present  aqueduct,  100,000,000  gallons 
per  day,  and  we  can,  if  needed  in  the  far  distant  future,  convey  to  the 
city  that  amount  of  water  from  the  Housatonic  river,  or  any  other 
proposed  auxiliary  to  the  Croton,  and  supply  a  population  of 
4,660,000  at  the  present  rate  of  consumption. 

3d.  Economy  of  first  cost  of  construction,  as   well  as  subsequent 

supervision  and  maintenance. 

The  cost  of  the  new  dam,  reservoir,  and  aqueduct, 
as  above  described,  including  everything  neces- 
sary to  deliver  the  water  into  Central  Park  reser- 
voir is  estimated  at   $14,000,000  00 


viii 


The  cost  of  a  new  aqueduct  of  I  50,000,000  gallons 
daily  capacity  by  one  of  the  two  routes  sur- 
veyed in  1875,  with  equal  storage  capacity  as 
included  in  the  new  plan,  and  provision  to  deliver 
the  water  in  the  Central  Park  reservoir,  is  esti- 


mated as  follows  : 

Sawmill  river  route. ...    $19, 493, 000  00 

Bronx  river  route   20,119,000  00 

Cost  of  new  plan  per  1 ,000,000  gallons  of  conduit 

capacity   48,000  00 

Cost  of  plans  reported  in  1875  per  1,000,000  gallons 
conduit  capacity  : 

Sawmill  river  route   103,946  00 

Bronx  river  route     108,121  00 

The  substitution  of  one  large  reservoir  in  place  of  eight  or  ten 


smaller  ones,  distributed  over  the  entire  water-shed,  and  the  con- 
struction of  the  shortest  practicable  conduit,  with  the  greatest  pro- 
portion of  rock  tunnel,  will  involve  much  less  labor  for  supervision 
and  maintenance  of  the  works  after  completion  than  the  works  pro- 
posed under  any  other  plan. 

In  conclusion,  I  can  only  repeat  what  I  stated  in  my  last  quarterly 
report,  that  the  character  and  reputation  of  the  eminent  engineers 
who  have  been  engaged  in  the  preparation  and  elaboration  of  this 
plan,  and  in  its  examination,  is  a  guarantee  that  their  conclusions  give 
the  best  results  which  patient  investigation,  guided  by  professional 
ability,  experience  and  judgment  can  secure. 

Very  respectfully, 

HUBERT  O.  THOMPSON, 

Commissioner  of  Public  Works. 


NEW  YORK  WATER  SUPPLY. 


Department  of  Public  Works. 
Hubert  O.  Thompson,  Commissioner. 


ON   PLANS  PROPOSED   FOR   STORING  AND  CONVEYING   AN  ADDITIONAL 

WATER   SUPPLY   TO  THE  CITY. 

OPINIONS  OF  THE  CONSULTING  ENGINEERS. 

TABLES  OF  RAIN-FALL,   ETC.,  ETC. 

MAP   SHOWING   DRAINAGE   AREA   AND   AQUEDUCT  LINES. 


OF 


Isaac  Newton, 


Chief  Engineer  of  Croton  Aqueduct, 


NEW  YORK: 

MARTIN  B.  BROWN,  PRINTER  AND  STATIONER, 
49  and  51  Park  Place. 


1882. 


TABLE 


OF  CONTENTS. 


— •  O  o  *- — 

PAGE 

Report  of  Chief  Engineer   5 

Opinion  of  Consulting  Engineer   ooo 

Appendix,  Opinions  of  the  Consulting  Engineers,  etc. 

Opinion  of  John  B.  Jervis   23 

Opinion  of  James  B.  Francis   27 

Opinion  of  Robert  K.  Martin   3: 

Report  and  Estimates  of  the  Sawmill  river  and  Bronx  river  plans   33 

Estimate  for  conveying  water  from  north  side  of  High  Bridge  to  Central  Park  reservoir. .  .  4: 

Table  I.  Showing  waste  of  water  over  Croton  dam   42 

"    2.  Average  depth  in  Aqueduct  and  average  delivery  in  gallons  per  day   45 

'*    3.  Rain-fall  in  Croton  basin   47 

"    4.  Rain-fall  at  receiving  reservoir,   High   Bridge,    Fordham,  Tarrytown,  Sing 

Sing,  Croton  Dam,  and  Boyd's  Corners   49 

"    5.  Comparison  of  rain-fall  at  different  places   52 

"    6.  Rain -fall  at  North  Salem,  Croton  basin   53 

"    7.  Extract  from  report  of  Dr.  Daniel  Draper  for  1876  ;  drought  of  1876   55 

"    8.  Rain-fall  receiving  reservoir,  Central  Park   57 

"    9.  Rain-fall  at  West  Point   59 

"  10.  Storage  drawn  in  1880  and  1881   61 

"  11.  Existing  storage,  artificial  and  natural   62 

"  12.  Per  cent,  of  rain-fall  running  in  the  Croton   63 


Map  showing  drainage  areas  and  aqueduct  lines  to  face  page  63 


NEW  YORK  WATER  SUPPLY. 


IR,  EPO  IR,  T 

TO 

HUBERT  O.  THOMPSON, 

Commissioner  of  Public  Works, 

BY 

ISAAC  NEWTON, 

Chief  Engineer,  Croton  Aqueduct. 


Chief  Engineer's  Office,  ) 
New  YORK,  January  30,  1882.  j" 

Hon.  H.  O.  Thompson, 

Commissioner  of  Public  Works : 

Sir — I  beg  leave  to  present  the  following  report  of  the  result  of 
the  investigations  and  surveys  made  under  my  direction  since  my 
appointment  as  Chief  Engineer,  for  a  new  aqueduct  from  the  Croton 
river  to  New  York.  The  surveys  and  maps  previously  made, 
together  with  other  data  on  record,  have  been  of  great  value,  not  only 
in  the  positive  information  they  afford,  but  in  the  suggestions  they 
have  led  to. 

Surveys  for  an  additional  supply  made  since  the  construction  of 
the  present  aqueduct,  have  been  those  of  the  Croton  water-shed  of 
1857-58,  and  those  made  in  1875  under  General  F.  J.  Porter,  for  the 
Sawmill  river  and  Bronx  river  plans.  The  description  and  estimates 
of  the  cost  of  construction  for  both  these  plans  will  be  found  in 
Appendix  (i  A,"  attached  to  this  report. 

At  the  beginning  of  my  study  of  the  subject  of  bringing  additional 
water  to  the  City  of  Xe\v  York,  the  various  sources  from  which  it  has 


6 


been  proposed  to  obtain  this  supply  were  carefully  looked  into. 
These  sources  are  the  Croton,  the  Passaic,  the  Housatonic,  and  the 
Hudson  and  Hackensack  rivers,  and  Lakes  George,  Erie,  Ontario 
and  Champlain,  also  the  streams  in  Rockland  and  Orange  counties. 
The  use  of  wells  and  salt  water  to  be  raised  into  reservoirs  by  pumps 
for  auxiliary  supply  was  likewise  considered. 

All  the  sources,  i.  e.y  from  these  rivers  and  lakes,  with  the 
exception  of  the  Croton  and  Housatonic,  were  set  aside  as  being  out 
of  the  question  on  account  of  the  immense  cost,  or  uncertainty  of 
sufficient  supply ;  although  some  of  them  might  be  used  as  auxiliaries. 

Since  becoming  satisfied  that  the  Croton  river  is  by  far  the  most 
available  and  the  most  economical  source  of  supply,  I  have  simply 
endeavored  to  determine  the  best  plan  for  storing  and  conveying  the 
water  of  this  river  to  the  city. 

The  quality  of  the  Croton  as  a  pure  and  wholesome  water,  as  well 
as  the  geological  and  other  characteristics  of  the  river  basin  are  so 
well  understood,  that  nothing  on  the  subject  need  to  be  mentioned.* 

The  meteorological  history  of  the  water-shed  of  the  Croton,  as  far 
back  as  there  are  any  records,  shows  that  with  adequate  storage 
capacity  at  the  head  of  the  aqueduct,  an  average  daily  supply  of 
about  250,000,000  f  of  gallons  can  be  relied  upon  in  the  driest  years. 
The  area  of  over  23  miles  which  will  be  added  to  the  existing 
water-shed — i.  to  the  area  shown  on  the  water-shed  maps  of 
1857-58 — by  the  plan  to  be  hereinafter  described,  would  increase 
the  average  daily  supply  from  15,000,000  to  20,000,000  of  gallons, 
thus  making  the  total  average  daily  supply  of  about  265,000,000  to 
270,000,000  of  United  States  gallons.^ 

The  following  views  have  formed  the  basis  of  my  investigations 
and  have  led  to  the  conclusions  arrived  at  : 

1st.  The  Croton  water-shed  is  adequate  to  furnish  all  the  city  will 
need  for  many  years  to  come,  provided  adequate  storage  capacity 
is  provided. 

2d.  The  storage  reservoirs  must  ultimately  be  of  sufficient  capacity 
to  hold  all,  or  nearly  all  the  water  of  the  Croton  in  the  driest  years, 

*  See  Report,  App.  "A." 

f  See  rain-fall  and  other  tables  in  Appendix. 

X  The  utmost  safe  capacity  of  present  conduit  is  about  ioo,ooo,oco. 


7 


so  that  none,  or  but  very  little,  can  waste  over  the  dam.  And 
eventually  to  carry  over  a  portion  of  the  surplus  of  wet  years  to 
supply  the  deficiency  of  dry  ones. 

3d.  The  nearer  the  storage  reservoirs  to  the  entrance  of  the 
aqueduct,  if  they  are  of  sufficient  capacity,  the  greater  will  be  the 
quantity  of  water  that  can  be  gathered  from  the  entire  Croton  basin, 
and  the  more  rapidly  will  the  reservoirs  fill  again  after  being  drawn 
down.  The  time  required  to  fill  the  existing  storage  reservoirs  and 
lakes,  after  they  have  been  drawn  down,  is  a  warning  on  this  point 
which  should  be  heeded.  All  the  water  which  falls  on  that  part  of 
the  basin  situated  below  the  several  storage  dam  sites  shown  on  the 
maps  of  1857  and  1858,  above  what  is  necessary  to  supply  the 
aqueduct,  will  run  into  the  Hudson  river  over  the  waste-weir  of  the 
aqueduct  dam,  unless  storage  is  provided  at  that  point  ;  so  without 
a  reservoir  at  that  locality,  it  will  be  impossible  to  secure  storage  in 
the  dry  years.  Hence  storage  located  at  the  entrance  to  the  aqueduct 
is  in  the  most  advantageous  position. 

4th.  The  aqueduct  capacity  should  be  sufficient  to  convey  all  the 
water  available  from  the  Croton  valley  ;  it  should  also  be  enough  to 
convey  a  portion  of  the  water  from  other  sources  of  supply,  which 
can  be  led  into  the  Croton  basin. 

The  capacity  of  an  aqueduct  10  feet  in  diameter,  with  an  inclination 
of  1  foot  to  the  mile,  is  about  168,000,000  of  gallons  in  24  hours  ; 
while  the  capacity  of  an  aqueduct  12  feet  in  diameter,  with  the  same 
inclination,  is  no  less  than  270,000,000  in  the  same  time.  The 
excess  of  cost  of  the  12  feet  over  the  10  feet  conduit  is  believed  to 
be  of  much  less  importance  than  the  greater  capacity  obtained. 

5th.  The  aqueduct  as  far  as  possible  should  be  in  tunnel,  this 
construction  being  the  safest,  most  durable,  and  the  least  exposed  to 
malicious  damage.  The  difference  in  the  cost  between  tunneling  and 
excavation,  because  of  the  improved  appliances  now  available,  has 
been  greatly  reduced  since  the  Croton  aqueduct  was  constructed  ; 
and  the  saving  in  length  of  conduit  which  can  be  effected  by  tunneling 
over  a  construction  on  a  line  located  on  or  near  the  surface  of  the 
ground,  added  to  the  decreased  land  damages,  will  probably  make  the 
former  fully  as  economical  even  in  first  cost. 

6th.  Wherever  it  is  necessary  to  cross  depressions  in  the  line,  the 


8 


aqueduct  should  be  carried  on  masonry  laid  in  mortar,  or  beneath  the 
surface  by  syphons. 

7th.  Storage  in  the  Croton  basin  is  preferable  to  bringing  water 
from  the  Housatonic  for  the  purpose  of  providing  against  deficiency 
in  the  natural  flow  of  the  Croton.* 

LOCATION  OF  NEW  AQUEDUCT  DAM. 

It  is  evident  this  dam  must  be  on  one  of  three  general  sites  :  1st. 
It  may  be  above  the  present  dam.  2d.  The  present  dam  may  be 
used  or  another  built  immediately  below  it  so  as  to  raise  the  level  of 
the  Croton  Lake.  3d.  It  may  be  on  the  river  considerably  below  the 
existing  Croton  dam  and  embrace  an  additional  drainage  area  to  that 
which  now  supplies  the  city. 

As  to  the  first  site,  taking  that  chosen  by  the  surveys  of  1875  to 
be  the  most  eligible  for  this  locality.  It  is  5  68-100  miles  above  the 
entrance  to  the  existing  aqueduct.  Here  the  topography  of  the 
country  is  such  that  it  is  not  practicable  to  raise  the  dam  sufficiently 
above  the  grade  of  the  proposed  aqueduct  to  make  a  reservoir  which 
would  store  any  considerable  amount.  A  large  area  of  country  would 
be  flooded  merely  to  get  water  into  the  aqueduct,  and  large  portions 
of  this  area  would  be  shoal  water. 

The  plans  of  1875  contemplated  a  dam  30  feet  higher  than  the 
present  one,  with  no  storage  above  the  level  required  to  keep  the 
aqueduct  full. 

Those  plans  require  10.6  miles  on  Sawmill  river  route,  and  13  98-100 
miles  on  the  Bronx  to  be  in  tunnel,  and  would  increase  the  length  of 
the  aqueduct  from  its  commencement  on  the  Croton  to  the  High 
Bridge  3  21-100  miles  more  than  the  present  one,  and  nearly  10  miles 
more  than  the  line  located  this  year. 

An  aqueduct  might  be  supplied  from  the  level  of  the  present  lake, 
and  about  1^  miles  above  the  present  dam  near  Trout  brook,  and 
join  the  new  line  near  the  Pocantico  river,  making  the  length  of 
conduit  to  High  Bridge  about  27^  miles. 

*  Should  the  Croton  basin  ever  prove  inedequate  to  supply  the  city,  it  is  possible  that  a 
supply  may  be  obtained  within  the  State  of  New  York  by  crossing  the  Hudson  by  tunnel  near 
Croton  Point.  When  the  time  arrives  this  no  doubt  will  be  carefully  examined  before  it  is 
finally  decided  to  construct  conduits  from  other  sources. 


9 


Take  next  the  second  site,  near  the  present  dam.  It  is  regarded 
as  impracticable  to  raise  this  dam,  and  the  valley  immediately  below 
is  not  well  adapted  for  another  of  much  greater  height.  These  plans 
moreover,  would  be  inadequate  without  the  construction  of  large 
storage  reservoirs  on  the  various  branches  of  the  Croton  to  secure  a 
full  supply  of  water  for  the  aqueduct. 

Take  the  third  site  ;  a  considerable  distance  below  the  present 
dam.  An  examination  of  the  Croton  river  below  this  point  to  the 
Hudson,  pointed  out  an  apparently  favorable  dam  site  near  Quaker 
Bridge,  about  4  50-100  miles  below  the  Croton  dam,  provided  a  rock 
foundation  could  be  found. 

The  geological  characteristics  of  the  valley  and  the  sinking  of  pits 
led  to  making  surveys  for  a  dam  at  this  place.  The  top  water- 
line  for  the  reservoir,  or  lake,  as  it  would  truly  be,  was  run  at  200 
feet  above  mean  tide,  Croton  grade.  The  present  Croton  lake  is 
166  17-100  feet  above  same  datum.  Calculations  based  upon  these 
surveys  show  that  the  reservoir  would  contain  over  32,000,000,000 
of  United  States  gallons  of  storage,  above  the  level,  necessary  to 
supply  an  aqueduct  capable  of  conveying  about  250,000,000  per 
day  to  the  city ;  or  with  a  delivery  of  200,000,000  per  day 
(twice  our  present  supply),  the  aqueduct  would  be  supplied  for  160 
days  without  a  gallon  from  the  natural  flow  of  the  Croton.  The 
existing  storage  in  reservoirs  and  lakes  is  9,000,000,000  ;  the  reser- 
voir which  will  be  begun  in  the  spring,  in  order  to  place  the  full 
daily  supply  of  100,000,000,  the  full  capacity  of  present  aqueduct, 
beyond  all  doubt,  and  which  is  to  contain  about  5,000,000,000,  would 
make  the  total  storage  nearly  46,000,000,000  of  gallons  ;  sufficient 
to  keep  up  a  daily  supply  of  200,000,000,  for  nearly  230  days  with- 
out the  natural  flow  of  the  Croton. 

The  great  area,  3,635  acres,  and  great  average  depth  of  this  new 
Croton  lake  would  make  it  exceedingly  valuable  as  a  settling  basin. 
The  benefits  of  such  a  condition  of  the  water  supply  can  scarcely  be 
overestimated,  and  hence  the  earnest  efforts  to  take  advantage  of 
them. 

The  dam  now  proposed  is  a  work  that  would  have  been 
considered,  at  the  time  of  the  construction  of  the  present 
aqueduct,  of  too  great  magnitude  to  be  undertaken.   The  remarkable 


IO 


progress  of  engineering  since  then  makes  such  a  structure  the  most 
advisable  in  this  case.  Successful  works  of  the  same  character  in 
France  have  given  great  satisfaction,  and  confirm  fully  the  theories 
on  this  subject  of  Messrs.  Montgolfier  and  Delocre,  of  France,  and 
Professor  Rankine,  of  England.  The  estimate  of  the  cost  of  this 
dam,  has  been  based  upon  no  untried  principles,  but  upon  those 
so  ably  advocated  by  the  eminent  engineers  above  mentioned,  and  so 
signally  justified  by  actual  experience. 

It  may  here  be  mentioned  that  stone  dams  of  nearly  this  height 
have  existed  in  Spain  for  a  long  time,  and  have  been  proposed 
elsewhere.  In  fact,  we  find,  that  as  far  back  as  1835,  a  dam  150 
feet  high  was  proposed  near  the  mouth  of  the  Croton,  for  an 
aqueduct  to  supply  this  city.  That  dam,  however,  as  far  as  the 
existing  plans  show,  was  entirely  different  in  character  from  the  one 
now  recommended,  not  being  in  accordance  with  the  principle  so 
successfully  carried  out  in  France.  Besides,  it  did  not  provide  for 
any  important  amount  of  storage  above  the  level  of  top  water  in  the 
aqueduct ;  whereas,  the  great  value  of  the  one  now  recommended 
consists  in  storage  capacity,  sufficient  to  furnish  200,000,000  gallons 
daily  for  160  days.  Without  this  capacity  it  would  probably  be  much 
cheaper  to  draw  the  city's  supply  from  the  present  Croton  lake. 


1 1 

AREA    AND    CAPACITY    OF  PROPOSED    NEW    CROTON    LAKE  NEAR 

QUAKER  BRIDGE. 


H.LEVATION 
ABOVE 

Mean  Tide, 
Feet. 

No.  of  Acres,  t 

Cubic  Feet, 
Not  Including 

I^Dr»TA\T     T     A  f  D 

V^KUIUIN  LAK.c« 

U.  S.  Gallons, 
Not  Including 

1   prim m   T  avc 

30 

7 

2,230,000 

16,680,400 

40 

37 

14,080,000 

105,318,400 

50 

55 

31,690,000 

237,041,200 

60 

85 

58,850,000 

440, 198,000 

70 

146 

105,600,000 

789,888,000 

80 

201 

169,960,000 

1,271,300,800 

90 

262 

253,790,000 

1,898,349,200 

ICO 

334 

360,730,000 

2,698,260,400 

no 

398 

488,160,000 

3,651,436,800 

120 

4i7 

639,130,000 

4,780,692,400 

130 

562 

819,007,000 

6,126,643,600 

140 

649 

1,026,860,000 

7,680,912,800 

150 

733 

1,261,540,000 

9, 436,3!  9, 200 

160 

1,245 

1,600,140,000 

12,417,847,200 

170 

•i5756 

2,222,350,000 

16,623,178,000 

180 

2,412 

2, 994, 59°, 000 

22,399,533,°°° 

190 

3,037 

3,966,930,000 

29,672,636,400 

200 

3,635 

5,130,740,000 

38,377.935,200 

Your  predecessor,  the  Hon.  Allan  Campbell,  an  engineer  of 
large  experience,  and  who  gave  great  attention  to  the  water  supply 
in  his  report  of  August  12,  1879,  referring  to  the  storage  reservoirs 
laid  down  on  the  water-shed  maps  of  1857,  says  :  "  It  is  estimated 
"  that  the  average  cost  per  million  gallons  of  all  reservoirs  projected 
"  in  the  Croton  basin  will  be  $200,"  and  in  the  same  report, 
referring  to  the  storage  capacity  required  for  the  proposed  aqueduct 


*  Croton  datum. 

t  The  area  of  present  Croton  lake  is  included  after  the  level  of  present  dam  is  reached. 


I  2 


of  1875:  "To  supply  another  aqueduct  with  150,000,000  daily, 
"  also  on  the  basis  of  the  driest  years,  additional  storage  to  the 
"  amount  of  about  30,000,000,000  gallons  must  be  provided," 
which  would  then  make  the  cost  of  the  necessary  storage 
$6,000,000. 

When  it  is  remembered  that  the  reservoirs  projected  in  the  Croton 
basin  would  flood  for  the  most  part  fertile  valleys,  probably  the  best 
land  in  Putnam  County,  $200  per  1,000,000  gallons  can  hardly 
be  considered  too  large  an  estimate  for  the  total  expense  of  all 
kinds  necessary  for  impounding  water.  If  a  reservoir  can  be  built  on 
the  site  above  pointed  out  and  contain,  as  above  stated,  32,000,000,000 
of  storage,  the  city  can  then  afford  to  expend  nearly  $6,500,000 
for  such  a  work  considered  as  a  storage  reservoir  dam. 

Owing  to  the  sterile  and  rocky  character  of  most  of  the  land  this 
reservoir  will  flood,  as  well  as  its  vast  dimensions  as  compared  with 
the  size  of  the  dam,  it  is  estimated  as  hereinafter  stated  that  the  total 
cost  of  the  reservoir,  including  dam,  will  not  be  over  $4,000,000. 

But  the  storage  it  will  contain  is  not  the  only  advantage  of  a 
reservoir  of  this  capacity,  and  located  in  this  place. 

1st.  It  saves  nearly  10  miles  in  length  of  aqueduct  over  the 
location  of  dam  made  in  1875,  and  this  saving  would  go  far  towards 
paying  the  whole  cost  of  this  reservoir. 

2d.  It  is  at  the  lowest  end  of  the  drainage  of  the  Croton,  and  would 
collect  water  more  rapidly  and  completely  than  other  plans. 

3d.  It  would  add  about  23  square  miles  to  the  area  of  the  water- 
shed, equivalent  to  an  average  daily  supply  of  from  15,000,000  to 
20,000,000  of  gallons. 

4th.  It  would  afford  a  settling  basin  of  the  grandest  proportions  ; 
the  loss  would  be  much  less  from  evaporation  and  other  sources  on 
account  of  greater  average  depth.  It  would  avoid  conveying  the 
water  through  miles  of  rivers,  brooks,  and,  in  many  cases  swamps, 
before  it  reaches  the  aqueduct,  while  in  very  cold  weather  the  supply 
from  such  sources  might  be  wholly  cut  off  by  frost,  as  was  the  case 
{with  the  water  from  the  storage  reservoirs)  in  the  winter  of  1880-81. 

The  difference  in  the  cost  between  a  dam  and  land  necessary  to 
raise  the  water  near  Quaker  bridge  142  feet  above  tide — which  is 
the  level  necessary  to  fill  the  aqueduct — and  what  would  be  necessary 


l3 


to  raise  it  200  feet,  is  estimated  to  be  about  $2,000,000.  Hence  the 
cost  of  the  storage  for  32,000,000,000  would  be  about  $60  per  million 
of  gallons,  instead  of  $200,  the  cost  per  million  by  building  on  the 
sites  far  up  in  the  Croton  basin  ;  or  $2,000,000  instead  of  $6,400,000, 
for  the  same  amount  of  storage,  even  if  it  could  be  collected  in 
reservoirs  higher  up  in  the  basin,  as  laid  down  on  the  Water-shed 
Map. 

STORAGE. 

The  water-shed  survey  executed  in  1857-58,  as  before  stated,  was 
made  chiefly  for  the  purpose  of  selecting  the  most  available  sites  for 
storage  reservoirs. 

The  following  table  contains  a  list  of  the  sites  then  selected, 
together  with  other  information  of  the  utmost  importance  in  studying 
this  subject  in  order  to  reach  a  safe  determination  respecting  the 
quantity  of  storage  that  can  be  secured  in  the  Croton  water  shed  by 
those  reservoirs. 


T4 


RESERVOIR  SITES. 

Table  from    Water-shed  Map   of  1857-58   of  Croton   Basin   above  the  present  Croton 

Aqueduct  Dam. 


Reservoir. 

Area. 

Capacity. 

Drainage  Area. 

Extreme    Depth  of 
Dam. 

1 

Extreme    Length  of 
Dam. 

Length  of  Reservoir. 

Distance  from  Crot  n 
Dam. 

Elevation  above  Mean 
Tide. 

Acres. 

Gallons. 

C/-i 

bq. 

TV  \  *  1  s-\  j— 

Miles. 

Feet. 

Feet. 

r  eet. 

Miles. 

r  eet. 

A  

485 

00 

5,211,015,625 

20 

45 

64 

1,500 

12,300 

9.500 

390 

B  

1 92 

00 

1,701,835,337 

15 

2000 

55 

I,70O 

6,000 

12.750 

500 

C  

73° 

00 

6,589,101,562 

:3 

7100 

43 

1,700 

16,600 

14.3OO 

550 

D  

1,008 

00 

9>°33>632,8i2 

41 

.9500 

48 

770 

21,000 

20.250 

5°o 

E  

303 

00 

3,369,206,857 

20 

3700 

64 

700 

7,500 

23-75° 

600 

F  

600 

75 

6,120,335,937 

12 

5100 

20.90 

1,560 

10,600 

I5-500 

•  56° 

G  

452 

19 

4,861,035,156 

20 

•9045 

73 

541 

12,200 

18.700 

375 

H  

384 

67 

2,490,062,500 

75 

4574 

40 

545 

14,748 

I9.39O 

375 

I 

449 

00 

4,205,820,654 

70 

•5230 

62 

33i 

12,745 

20.447 

4i5 

J  

191 

38 

2,314,074,703 

11 

.9171 

69 

i,3" 

11,616 

28.710 

500 

K  

512 

74 

5,671,449,219 

78 

9000 

72 

9°4 

14,809 

I5-2I5 

275 

L  

262 

75 

2,328,217,733 

26 

.8600 

74 

757 

13,120 

16.539 

295 

M  

492 

25 

4,392,131,445 

23 

•3449 

72 

925 

12,300 

I3-83I 

316 

N  

197 

00 

1,676,049,171 

30 

9620 

60 

686 

8,650 

7.708 

250 

O  

239 

47 

2,182,337,109 

17 

■3170 

90 

1,170 

7,629 

9.970 

305 

Entire  drainage  area  of  Croton  Basin,  338  82-100  square  miles. 


The  total  drainage  area  of  all  these  reservoirs  foots  up  480.30 
square  miles,  while  the  entire  area  of  the  Croton  basin  is  338.82  square 
miles ;  this  is  because  the  computed  drainage  of  some  of  the 
reservoirs  overlaps  that  of  others,  which  shows  that  the  Croton 
Aqueduct  Board  did  not  contemplate  that  all  of  these  sites  could  be 
made  available  as  reservoirs  to  the  extent  indicated  by  this  table. 

The  drainage  of  some  of  them  is  so  small  that  in  a  dry  year  they 
probably  would  not  fill  ;  for  example,  reservoir  F,  which  has  a 


15 


drainage  area  of  but  12  51-100  square  miles  with  a  capacity  of  6, 120,- 
000,000  gallons.  An  inspection  of  this  map  shows  that  if  every  one 
of  these  reservoirs  were  built  they  would  not  receive  the  drainage  of 
over  about  200  square  miles,  because  they  do  not  furnish  storage  for 
the  waters  of  large  areas  for  which  reservoir  sites  have  not  been  found. 
The  total  estimated  capacity  of  these  reservoirs  is  62,000,000,000  of 
gallons  ;  of  this  amount  8,230,000,000  is  already  secured  by 
reservoirs  E  and  G,  which  have  been  built,  one  at  Boyd's  Corners, 
the  other  on  the  middle  branch  of  the  Croton  ;  this  leaves  53,770,- 
000,000  as  the  remaining  storage,  assuming  the  drainage  to  be 
adequate  to  fill  the  reservoirs.  It  has  been  estimated  that  to 
supply  another  aqueduct  on  the  basis  of  the  driest  years,  with 
1 50,000,000  daily,  additional  storage  to  the  extent  of  about 
30,000,000,000  must  be  provided  ;  but  as  before  stated,  if  all  these 
reservoirs  could  be  built  they  could  only  receive  the  drainage  of 
about  two-thirds  of  the  Croton  basin.  The  balance  of  the  drainage 
above  the  quantity  necessary  to  supply  the  conduits  would  find  its 
way  into  the  Hudson  over  the  waste-weir  of  the  dam,  if  not 
secured  near  the  mouth  of  the  Croton.  It  is  extremely  doubtful  if 
even  30,000,000,000  gallons  could  be  secured  beyond  all  per- 
adventure  by  constructing  storage  reservoirs  in  the  water-shed  many 
miles  above  the  entrance  of  the  aqueduct.  In  short,  the  only  way  to 
secure  the  entire  flow  of  the  Croton  in  the  driest  years,  is  to  have 
large  storage  capacity  near  the  mouth  of  the  river. 

THE  HOUSATONIC  AS  A  FEEDER  FOR  NEW  AQUEDUCT. 

As  stated  in  the  quarterly  report  for  August,  1879,  surveys  were 
made  for  diverting  the  waters  of  the  Housatonic  into  the  Croton 
water-shed  as  a  feeder  for  a  new  and  large  aqueduct.  The  plan 
proposed  for  conveying  this  water  to  the  Croton,  in  general  terms, 
was  mainly  an  open  canal  with  a  sectional  area  of  80  square  feet,  and 
an  inclination  of  one  foot  to  the  mile,  the  calculated  capacity  being 
100,000,000  gallons  daily.  The  comparison  of  this  plan  of 
obtaining  water  for  the  new  aqueduct  with  that  of  storage  has  been 
carefully  studied  in  all  its  bearings. 

The  Housatonic  is  in  Massachusetts  and  Connecticut,  out  of  the 
authority  of  this  State,  which  could,  therefore,  exercise  no  control  over 


i6 


it,  to  prevent  pollution,  or  enforce  any  regulations.  The  water  would 
have  to  traverse  about  eighty  miles  with  exposed  surface  before 
reaching  the  aqueduct,  and  in  very  cold  weather  there  would  be  great 
danger  of  the  supply  being  cut  off  or  greatly  diminished  when  the 
demand  would  be  greatest. 

This  river  is  no  doubt  liable  to  the  same  fluctuations  of  volume  as 
the  Croton,  and  there  is  no  probability  that  in  a  season  of  extreme 
drought  100,000,000  per  day  estimated  could  be  obtained  ;  but  if  it 
could,  the  damages  to  mill  rights  would  doubtless  swell  the  cost  much 
beyond  the  estimate.  It  would  be  necessary  not  only  to  pay  for  all 
rights  injured  below  the  point  of  intake,  but  for  preventing  mill 
owners  above  from  holding  back  water  nights  and  Sundays  during 
seasons  of  drought.  The  yield  of  the  Croton  basin  averaged  during 
August,  1878,  123,000,000  of  gallons  daily;  in  December,  1880,  its 
average  was  but  33,000,000,  showing  a  falling  off  of  73  per  cent.  This 
proportion  applied  to  the  Housatonic  shows  that  it  could  not  be 
relied  upon  to  furnish  more  than  54,000,000  a  day,  because  the  avail- 
able area  of  the  Housatonic  basin  is  only  about  double  that  of  the 
Croton.  If  the  lowest  daily  yield  of  the  Croton  be  taken,  now  known 
to  be  only  about  10,000,000,  then  the  Housatonic  could  not  be  relied 
upon  for  more  than  about  20,000,000  daily. 

The  following  table  gives  an  estimate  of  storage  required  to  supply 
conduits  with  300  millions  daily,  supposing  a  year  as  dry  as  that  of 
1880,  the  driest  yet  known  in  the  Croton  Basin. 

For  May   3,797,500,000  gallons. 

For  June   5,962,500,000 

For  July   6,130,560,000 

For  August   6,200,000,000 

For  September   6,000,000,000  " 

For  October    6,200,000,000 

For  November   5,820,000,000 

For  December   6,147,000,000 

Drawn  from  storage  reservoirs   8,530,000,000 


* « 


54>787,56o,ooo  gallons. 


i7 


Existing  storage  ponds  and  reservoirs 

Quaker  Bridge  reservoir  

Reservoir  I,  to  be  built  

Still  required  


$9,000,000,000 
32,000,000,000 
5,000,000,000 
9,000,000,000 


55,000,000,000 


If  the  difference  in  cost  was  in  favor  of  the  Housatonic  plan,  as 
compared  with  that  of  constructing  storage  reservoirs  on  the  Croton, 
the  disadvantages  the  former  presents  are  so  great  as  to  be  decisive 
against  it. 

HEAD  OR  LEVEL  OF  THE  NEW  SUPPLY  IN  NEW  YORK  CITY. 

It  is  seen  by  the  description  of  the  Sawmill  river  and  Bronx  river 
plans,  that  the  aqueduct  proposed  was  to  end  near  Jerome  Park, 
3  01-100  miles  from  High  Bridge  and  7  88-100  miles  from  the  receiv- 
ing reservoir  in  the  Central  Park.  At  Jerome  Park  there  was  to  be 
constructed  a  receiving  reservoir  of  600,000,000  gallons  capacity. 
The  elevation  of  the  new  aqueduct  at  Jerome  Park  was  to  be  30  feet 
higher  than  the  present  one  ;  but  a  small  proportion  of  this  increased 
head  would  be  available  in  the  circulation  on  Manhattan  Island, 
because  the  water  was  to  be  conveyed  from  Jerome  Park  reservoir  to 
High  Bridge  and  from  thence  under  the  Harlem  river  to  the  Central 
Park  reservoir  in  cast  iron  pipes  48  inches  in  diameter. 

If  ten  lines  of  pipes  of  this  diameter  were  laid  for  this  purpose  it 
is  calculated  that  the  loss  of  head  or  pressure  from  friction  alone 
would  be  about  20  feet,  when  the  aqueduct  is  discharging  its  full 
capacity,  by  the  time  the  water  reached  the  south  side  of  Harlem 
river.  As  the  main  discharge  would  be  into  the  Central  Park  reser- 
voir, the  pressure  at  which  water  could  be  delivered  from  that  source 
would  not  be  increased. 

The  new  works,  wholly  independent  of  the  Croton,  now  being 
constructed,  to  convey  the  waters  of  the  Bronx  and  Byram  rivers  will 
deliver  water  into  reservoirs  to  be  built  at  William's  Bridge  at  an 
altitude  of  about  180  feet  above  tide,  or  about  50  feet  higher  than  the 
present  aqueduct,  and  the  water  which  will  be  supplied  from  this 


2 


i8 


source  will  suffice  for  the  more  elevated  portions  of  the  Twenty-third 
and  Twenty-fourth  Wards.* 

No  provision  has  been  made  in  the  Quaker  Bridge  plans  for 
additional  storage  reservoirs  within  the  city  limits.  The  principal 
function  of  such  reservoirs  is  to  keep  a  supply  in  the  city  in  case  it  is 
necessary  to  shut  off  the  aqueduct.  Hence  the  necessity  for  storage 
at  this  end  will  not  be  increased  by  building  another  aqueduct. 

Any  important  change,  with  the  view  of  raising  the  level  of  the 
top  water-line  of  the  Central  Park  reservoir,  would  involve  great 
expense,  and  could  not  in  any  event  materially  diminish  the  high 
service  area  necessary  to  be  supplied  by  pumping. 

THE  AQUEDUCT. 

Several  lines  have  been  run  in  order  to  get  the  best  location  for 
an  aqueduct,  as  far  as  possible  in  rock  tunnel,  from  the  Quaker 
Bridge  reservoir  to  the  High  Bridge.  A  favorable  line  was  found 
which  measures  26^  miles  to  High  Bridge,  or  only  about  91-100  mile 
greater  than  an  air  line. 

This  line  is  remarkable  for  the  comparatively  small  depth  of  the 
shafts  necessary  for  constructing  the  tunnels,  which  is  a  matter  of 
great  importance,  both  with  respect  to  the  cost  and  time  required  to 
execute  the  work. 

There  would  be  required  33  shafts,  averaging  101  feet  in  depth, 
between  the  entrance  of  the  aqueduct  and  the  High  Bridge. 

It  is  proposed  to  cross  the  Harlem  river  by  a  syphon,  either 
tunnel  through  rock,  or  pipes  laid  on  river  bottom  ;  to  cross  Man- 
hattan Valley  by  a  similar  syphon,  and  to  build  the  rest  of  the 
aqueduct  between  the  south  side  of  Harlem  and  Central  Park  reser- 
voir in  tunnel  wherever  possible,  the  same  as  in  Westchester  County. 

It  is  proposed  to  make  the  aqueduct  a  circle  in  sections  lined  with 
brick,  12  feet  in  diameter,  and  to  have  it  leave  Quaker  Bridge  reser- 
voir of  New  Croton  lake  at  the  level  of  about  142  feet  above  tide,  thus 
permitting  58  feet  of  storage  to  be  drawn,  and  to  discharge  into  the 
Central  Park  reservoir  at  119  feet  above  the  same  datum. 

Acres. 

*  Area  of  Twenty -third  and  Twenty-fourth  Wards,  New  York  City   1 2,3 17 

Number  of  acres  below  100  feet  mean  tide,  Croton  datum,  to  be  supplied  from  aqueduct  8,352 

Number  of  acres  between  100  and  160  feet,  to  be  supplied  from  Bronx   2,617 

Number  above  160  feet,  to  be  supplied  from  Yonkers  or  by  pumping   Ij34^ 


19 


Such  a  conduit  would  have  the  capacity  to  deliver  about 
250,000,000  of  United  States  gallons  daily  when  filled  to  within  a 
few  inches  of  the  top. 

I  need  hardly  call  attention  to  the  great  advantages  a  conduit  in 
tunnel  presents  over  any  other  mode  ;  such  a  construction  would  be 
as  imperishable  as  any  structure  can  be,  and  it  is  no  small  matter 
that  it  would  be  removed  as  far  as  possible  from  the  danger  of  injury 
by  evil-doers. 

In  preparing  plans  and  making  estimates  for  this  conduit,  I  have 
had  the  invaluable  aid  of  unrestricted  access  to  all  the  plans  and 
other  data  connected  with  the  construction  of  the  Baltimore  aqueduct 
tunnel  from  Gunpowder  Creek,  kindly  granted  me  by  Robert  K. 
Martin,  the  Chief-Engineer  of  the  work.  As  this  tunnel  is  in  rock, 
and  of  the  same  size  and  character  as  the  one  herein  proposed,  we 
have  a  safe  guide  for  estimates  of  cost.  While  the  Croton  tunnels  are 
considerably  longer  in  the  aggregate  than  the  Gunpowder  (Baltimore) 
tunnel,  they  would  have  shafts  of  much  less  average  depth  and 
could  consequently  be  worked  more  rapidly  and  advantageously. 

TIME  REQUIRED  TO  COMPLETE  THE  PROPOSED  WORK. 

The  time  required  to  construct  the  Baltimore  tunnel  may  be  taken 
as  a  guide  in  estimating  the  time  necessary  to  complete  the  proposed 
Croton  tunnels  ;  as  the  drifts  in  the  proposed  work  would  be  about  the 
same  length  and  through  the  same  character  of  rock,  while  the  shafts 
would  be  considerably  less  in  depth,  it  can  be  executed  in  less  time, 
other  things  being  equal.  Taking  the  most  difficult  section  on  the 
proposed  line  as  the  portion  which  would  require  the  most  time,  and 
which  would  consequently  govern  the  completion,  it  is  estimated  that 
the  New  York  aqueduct  can  be  constructed  in  three  and  a  half  years 
from  time  of  commencement.  It  should  be  remembered  that  in 
tunnel  construction  the  work  would  be  carried  on  day  and  night, 
winter  and  summer. 

It  is  more  difficult  to  estimate  the  time  which  would  be  required  to 
complete  the  dam  ;  it  would  probably  be  found  necessary  to  suspend 
the  work  during  the  winter,  say  from  three  to  four  months  each  year  ; 
but  when  this  dam  has  reached  the  height  of  135  feet  above  mean 
tide,  or  119  feet  above  the  ground,  Croton  datum,  it  can  be  made 
to  supply  the  new  conduit  with  about  100,000,000  gallons  per  day  ; 


20 


it  is  probable  with  a  systematic  prosecution  of  the  work,  it  can  be 
raised  to  this  height  in  three  and  a  half  years,  while  a  year  and  a  half 
more  would  probably  complete  the  work  to  the  full  height."^ 

The  estimated  cost  of  the  proposed  aqueduct  from  Quaker  Bridge 
reservoir  to  the  receiving  reservoir  in  the  Central  Park  is  $10,000,000. 
As  before  stated,  in  making  these  estimates,  I  have  had  the  aid  of 
the  experience  gained  in  the  construction  of  the  Baltimore  tunnel  ; 
the  above  estimate  being  based  largely  on  that  data,  and  on  liberal 
prices  for  both  labor  and  materials,  it  is  believed  that  it  may  confi- 
dently be  taken  as  the  amount  within  which  the  work  can  be  done. 

The  proposed  dam  would  be  constructed  wholly  of  masonry  ; 
were  it  not  for  the  contingencies  which  may  arise  in  securing  a  proper 
foundation,  a  very  close  estimate  could  be  made  of  its  cost.  This 
being  the  case,  and  with  the  knowledge  of  the  ground  obtained  by 
over  one  hundred  test  pits  and  explorations  with  diamond  drills.  I 
have  estimated  an  amount  for  the  dam  and  reservoir  hereinbefore 
described  which  should  place  it  beyond  contingencies.  The  estimate 
for  the  dam  and  reservoir  is  $4, 000, 000,  t  which,  added  to  the  estimate 
for  the  aqueduct,  would  make  the  cost  of  the  new  water  supply 
$14,000,000.  The  details  of  these  estimates  are  ready  for  your 
inspection. 

I  estimated  early  last  summer  that  an  aqueduct  of  150,000,000 
daily  supply,  with  the  necessary  storage  capacity,  could  be  built  for 
$12,000,000;  subsequent  examination  has  shown  that  such  a  work 
could  be  constructed  for  less  than  that  amount.  But  increasing  the 
size  of  conduit  to  convey  250,000,000  per  day,  instead  of  150,000,000, 
the  total  cost  was  augmented  somewhat  over  $2,000,000  ;  the  excess 
in  cost  was  considered  small  to  expend  for  an  additional  daily  supply 
of  100,000,000  of  gallons. 

With  such  an  aqueduct  in  use  and  with  pipes  already  laid,  it  is 
safe  to  say  that  the  head  (or  pressure)  which  existed  when  the  Croton 
water  was  introduced  would  be  again  enjoyed,  provided  the  waste 
does  not  exceed  the  present  amount.  It  is  expected  that  the  Depart- 
ment will  be  able  to  diminish  the  waste. 

*  The  Furens  dam  in  France,  164  feet  high,  was  completed  its  full  height  in  four  years. 

f  Should  the  dam  owing  to  unexpected  difficulties  in  the  foundation  cost  one,  or  even 
three  millions  more  than  the  estimate,  the  Quaker  Bridge  plan  would  still  retain  its  decided 
superiority. 


2  I 

The  following  tables  give  the  comparative  cost  and  other  particu- 
lars of  the  three  plans  mentioned  in  this  report  : 

Table  of  Comparison  of  the  Plans  which  have  been  proposed  for  an  Aqueduct  from  the  Croton 
Basin  ;  with  Extension  from  High  Bridge  to  Central  Park  Reservoir. 


Quaker  Bridge, 
1881  Plan. 

Sawmill  River. 
1875  Plan. 

Bronx  River. 
1875  Plan. 

2.  Capacity  in  million  gallons  daily  

3.  Total  storage  provided  by  plan  in  Croton 

basin,  with  dams  just  high  enough  to 
fill  aqueduct,  million  gallons  daily .... 

4.  The  same  with  dams,  full  height  proposed, 

31-35 
250 

*  42.31 

*  41.17 
150 

32,000 
f  $12,000,000 
14,000,000 
2,000,000 
3,635 

5.  Total  cost  including    no    provision  for 

6.  Total  cost  including  provision  for  32,000,- 

7.  Cost  of  providing   32,000,000,000  gallons 

storage  in  Croton  basin  

8.  Area  of  new  lake  including  present  Croton 

%  $13,093,414 

§  19A93AH 
6,400,000 
1,200 

X  $13,719,529 
§  20,119,529 

6,400,000 
1,200 

*  From  profiles. 

■\  Estimate  for  aqueduct  to  High  Bridge  $10,000,000,  for  dam  without  storage  $2,000,000  (see  page  41) 
=  $12,000,000. 

J  Estimate  in  Appendix  "A  "added  to  Mr.  G.  W.  Birdsall's  estimate  (Appendix  "B")  for  conveying 
the  water  to  Central  Park  reservoir,  hy  the  plans  contemplated  in  1875. 
§  The  same  as  No.  5,  with  $6,400,000  for  storage  added. 

Table  of  Comparison  of  the  Plans  which  have  been  proposed  for  an  Aqueduct  from  Croton 

Basin,  terminating  at  High  Bridge. 

Quaker  Bridge 
Plan,  1881. 

Sawmill  River 
Plan,  1875. 

Bronx  River 
Plan,  1875. 

1.  Total  length  from  the  Croton  to  High 

Bridge,  miles  

2.  Capacity,  U.    S.    gallons  in   24  hours, 

3.  Total  cost  with  no  additional  storage  

4.  Total  cost  with  32,000,000,000  additional 

storage  in  Croton  basin  

5.  Cost  per  million  of    gallons    of  supply 

obtained,  including  32,000,000,000  ad- 
ditional storage  in  Croton  basin  

26.51 
250 

$10,000,000 
f  12,000,000 

48,000 

36.52 
I50 

*  $9,191,989 

X  15,591,989 
103,946 

36.08 
I50 

*  $9,818,104 

X  16,218,104 
108,121 

*  See  estimate  in  Appendix  "  A." 

t  Estimating  increase  in  height  of  dam  for  storage  to  be  $2,000,000,  see  page  13. 
t  Adding  cost  of  32,000,000,000  storage  at  $200  per  million. 


22 


A  large  amount  of  field  and  office  work  has  been  accomplished 
during  the  season,  among  other  things,  the  flow-line  of  Quaker  Bridge 
reservoir,  78  miles,  and  21^  miles  of  cross  section  lines  have  been 
run  ;  over  100  miles  have  been  run  in  Westchester  County.  A  great 
deal  of  detail  survey  has  been  done  to  determine  the  proposed  dam  site, 
besides  other  surveys  of  a  similar  character  ;  78  borings  to  rock  have 
been  made  in  Harlem  river  above  High  Bridge.  The  data  obtained 
from  the  U.  S.  Geodetic  and  Coast  Survey  has  been  a  valuable  aid  in 
topographical  work  along  the  line  of  proposed  aqueduct.  We 
have  had  the  advantage  of  the  trigonometrical  points  and  the  detail 
surveys  made  under  the  late  Professor  Bache  by  the  officers  of  the 
Coast  Survey.  Over  100  test  pits  have  been  put  down  on  the  pro- 
posed dam  site,  and  two  diamond  drills  are  accomplishing  good 
results  in  the  bed  of  the  Croton. 

I  have  studied  the  entire  subject  with  the  aid  of  E.  S.  Chesbrough, 
Consulting  Engineer.  B.  S.  Church,  Resident  Engineer,  from  his  long 
experience  with  the  existing  works  has  rendered  valuable  aid.  The 
topographical  work  has  been  under  the  immediate  charge  of  John 
Mechan,  formerly  of  U.  S.  Coast  Survey. 

I  am  indebted  to  J.  W.  Adams  for  assistance  in  making  up  the 
estimates,  as  well  as  details  of  plans  of  aqueduct  on  which  they  were 
based. 

Very  respectfully  submitted. 

ISAAC  NEWTON, 

Chief  Engineer. 


NEW  YORK,  January  31,  1882. 

Isaac  Newton,  Esq., 

Chief  Engineer  Croton  Aqueduct  : 

Dear  Sir — I  concur  with  you  in  the  views  and  recommendations 
of  your  report  on  the  proposed  additional  supply  of  water  for  this 
city. 

E.  S.  CHESBROUGH, 

Consulting  Engineer. 


APPENDIX. 




OPINION  OF  JOHN  B.  JERVIS,  Esq.,  CONSTRUCTOR  OF 

THE  CROTON  AQUEDUCT." 

Rome,  N.  Y.,  January  13,  1882. 

To  Isaac  Newton,  Esq., 

Chief  Engineer  Croton  Aqtceduct,  New  York  ; 

DEAR  Sir — I  acknowledged  your  favor  of  10th  December,  1881, 
also  that  of  December  26,  1881.  In  the  meantime  I  visited  your 
orifice  in  New  York,  and  obtained  a  knowledge  of  the  general  features 
of  the  plans  and  estimates  of  the  proposed  improvements  for  the 
supply  of  New  York  City  with  water.  After  full  consultation  with 
yourself  and  your  Consulting  Engineer,  I  now  propose  to  reply  to  the 
questions  you  have  propounded  to  me. 

First  Question. — As  to  the  Necessity  of  an  Additional  Supply  of 

Water. 

As  to  this  question,  it  does  not  appear  necessary  to  go  much  into 
detail.  For  several  years  instead  of  adding  to  the  supply  as  popula- 
tion increased,  the  over  strained  capacity  of  the  present  aqueduct  has 
been  the  same,  and  no  addition  has  been  practicable  to  the  supply 
needed  for  the  largely  increased  population. 

A  serious  failure  in  the  present  aqueduct,  which  has  been  a  source 
of  anxiety  for  several  years,  may  arrest  its  functions. 

New  York  has  a  very  large  shipping  interest,  that  needs  much 
wTater  ;  since  the  introduction  of  the  Croton,  her  manufactures  have 
largely  increased  ;  she  is  reported  now  the  largest  manufacturing  city 
in  the  United  States. 

The  present  population  is  too  large  to  depend  for  its  current 
supply  of  water  on  one  aqueduct.    Without  further  discussion  of  this 


*  Condensed  by  Mr.  Jervis  from  his  longer  report. 


24 


question,  I  have  no  doubt  that  the  important  interests  of  the  city 
demand  an  additional  conduit. 

Second  Question. — Source  of  Supply. 
I  noticed  by  the  reports  you  gave  me  that  surveys  have  been 
made,  establishing  the  practicability  of  obtaining  the  supply  from  the 
Housatonic  river  in  Massachusetts  and  Connecticut.  Whatever 
feasibility  there  may  be  of  drawing  from  this  or  any  other  source,  it 
appears  to  me  better  that  it  should  be  held  in  reserve  until  the 
supply  from  the  Croton  valley  is  exhausted. 

THIRD  QUESTION. — Position  of  Reservoirs  for  Storage — Importance 
of  having  them  Large  and  well  down  the  Stream. 

Xo  doubt,  large  reservoirs  are  to  be  preferred  and  the  nearer  the 
lower  end  of  the  valley,  the  more  effectual  will  they  be  to  secure 
the  whole  drainage  of  the  basin.  The  securing  of  large  reservoir 
sites,  instead  of  several  small  ones,  is  decidedly  important  in  securing 
pure  water.  The  high  dam  at  the  lower  end  of  the  valley  certainly 
provides  for  the  most  efficient  method  of  securing  the  entire  drainage 
of  the  Croton  valley. 

FOURTH  QUESTION. — Practicability  of  a  High  Stone  Dam — Its 
Safety — Precautions  to  be  Observed ;  Means  of  Passing  Flood 
Water  during  Co?istruction  of  the  Foundation — HtigJit  of  Main 
Dam  above  Flow-line — 'Le?igth  of  Waste-weir  and  Height  of  Water 
to  be  permitted  above  Flow-line  during  and  after  Greatest 
Storms. 

As  to  general  practicability,  I  have  no  doubt  ;  but  it  will  be  a 
high  dam,  so  far  as  can  now  be  judged,  about  230  feet  above  rock 
bottom,  or  180  feet  above  surface  of  ground.  You  may  require  to 
go  lower  to  secure  a  rock  foundation  for  the  highest  part  ;  your 
soundings  not  being  complete,  I  do  not  think  you  will  have  to  go 
materially  lower  than  now  appears  probable. 

There  will  be  no  difficulty  in  making  a  wall  of  hydraulic  masonry 
sufficient  to  sustain  it  against  the  power  of  the  water  above  from 
overthrowing  it. 

The  main  question  will  be  the  power  of  the  material  to  resist  the 
crushing  force  of  this  weight. 


25 


I  think  you  will  have  no  difficulty  in  obtaining  stone  in  the 
vicinity  of  the  location  that  will  sustain  the  pressure.  Good  brick 
will  bear  near  four  times  the  weight  without  crushing.  I  have  no 
hesitation  in  expressing  the  opinion  that  the  Ulster  cement,  with  clean 
sand,  will  make  mortar  and  concrete  sufficient  for  this  work.  If  you 
can  find  cement  that  is  stronger,  it  will  be  prudent  to  use  it  in  the 
lower  section  of  the  dam. 

Means  of  Passing  Floods  during  Construction. 
The  floods  of  the  river  will,  no  doubt,  embarrass  the  work  of 
construction,  and  as  this  will  be  a  work  of  years,  the  precautions 
should  be  very  efficient.  Such  a  work  cannot  be  executed  without 
many  contingent  embarrassments,  and  you  will  find  occasion  for  the 
most  vigilant  assiduity  and  your  best  professional  judgment  will  be 
demanded. 

The  Height  of  Dam  above  Flow- line — Length  of   Waste-weir  and 

Height  above  Flow  in  Floods. 

The  old  dam  has  a  waste-weir  of  270  feet.  In  about  40  years  since 
its  construction,  no  flood  has  been  reported  except  in  one  instance  of 
a  rise  of  8  feet  above  the  crest  of  the  dam. 

If  I  understand  the  location,  and  I  have  no  doubt  it  was  well 
explained  to  me,  the  facilities  for  a  waste-weir  in  the  proposed  dam 
are  very  good.  Its  position  will  be  in  the  subsidiary  dam  that  is 
required  north  of  the  main  dam,  where  the  waste-weir  and  the 
channel  from  it  will  be  in  solid  rock. 

Fifth  Question.  —  Conduit  in  the  Tunnel  as  much  as  possible, 
instead  of  an  Fmbankment  or  in  slight  Excavations. 

There  can  be  no  question  that  a  conduit  in  a  tunnel  through 
solid  rock  will  be  more  safe,  and  require  less  repair  than  one  on  any 
kind  of  filling  or  in  light  cuttings. 

In  some  cases  the  cost  of  filling  in  low  grounds  would  be  greater 
than  that  of  tunnel  in  sound  rock. 

Sixth  Question. — Difference  in  Cost  of  Conduit  of,  say,  1 50,000,- 
000  daily  and  one  of,  say,  200,000,000  to  250,000,000  not  Equal  to 
the  Value  of  the  Increased  Capacity. 

It  would  require  more  calculations  than  I  am  now  able  to  make,  to 
determine  what  the  difference  of  value  may  be.    There  is,  however. 


26 


no  doubt  the  large  conduit  will  be  less  expensive,  as  compared  to 
capacity,  than  the  smaller  one. 

SEVENTH  Question. — Level  of  Central  Park  Reservoir  to  be  Main- 
tained in  New  Works,  but  General  Head  throughout  the  City  to  be 
greatly  improved  by  Additional  Supply,  probably  without  New 
Mains  at  first. 

The  new  aqueduct  will  greatly  improve  the  facility  for  keeping  full 
head  in  the  city  reservoirs,  and  consequently  maintain  more 
efficiency  in  the  pressure  on  the  distribution  pipes.  Whether  an 
increase  of  the  city  mains  may  be  found  necessary,  will  depend  on 
the  experience  of  the  effect  of  a  full  head  in  the  reservoirs. 

EIGHTH  Question. — Danger  to  a  City  of  the  Importance  and 
Magnitude  of  New  York,  of  depending  wholly  on  one  Aqueduct. 

As  to  the  propriety  of  a  second  aqueduct  there  can  be  no  doubt. 

Finally,  I  would  say  : 

1st.  The  dam  you  propose,  is  practicable. 

2d.  That  it  is  the  best,  and,  in  fact,  the  only  plan  that  can  secure 
the  whole  source  of  the  Croton  valley  for  the  supply  of  its  waters  to 
the  City  of  New  York. 

3d.  Furnishing,  as  it  does,  a  reservoir  of  large  capacity,  it  provides 
a  supply  of  water  of  the  purest  condition  practicable. 

4th.  Though  there  will  be  more  or  less  embarrassment  from  the 
floods  of  the  river  during  construction,  there  is  no  reason  to  doubt 
they  may  be  .successfully  overcome  by  the  engineering  skill  you  will 
be  able  to  exercise  on  this  subject. 

5th.  As  to  line  and  plan  of  aqueduct  you  propose,  I  see  nothing 
to  suggest.    Your  view  of  this  I  regard  as  well  taken. 

When  the  dam  is  carried  to  the  height  of  the  gate  chamber,  you 
can  occupy  the  new  aqueduct,  should  it  be  ready.    This  you  will  see. 

With  sincere  wishes  for  your  success  in  the  construction  of  this 
rather  bold,  but  eminently  important  and,  as  I  believe,  quite 
practicable  work,  I  submit  this  paper. 

Very  respectfully, 

JOHN  B.  JERVIS, 

Consulting  Engineer. 


27 


OPINION  OF  JAMES  B.  FRANCIS,  Esq.,  PRESIDENT  OF 
AMERICAN  SOCIETY  OF  CIVIL  ENGINEERS. 

Isaac  Newton,  Esq., 

Chief  Engineer  of  Croton  Aqueduct  : 

Dear  Sir — In  reply  to  your  communication  of  the  ioth  instant, 
requesting  my  opinion  of  the  advisability  of  obtaining  an  additional 
supply  of  water  for  the  City  of  New  York,  by  the  plan  you  describe, 
I  have  to  say  that,  in  addition  to  the  brief  description  in  your  com- 
munication, I  have  been  informed  verbally  by  yourself  and  Mr.  E.  S. 
Chesbrough  more  fully  on  the  subject  ;  have  read  various  printed 
reports  and  documents  relating  to  the  general  subject  of  the  water 
supply  of  the  city  ;  examined  the  maps,  plans,  and  profiles  of  pro- 
posed plans  in  your  office,  and  have  made  a  personal  examination  of 
the  site  of  some  of  the  proposed  works. 

From  information  gathered  as  above,  I  beg  leave  to  offer  the 
following  remarks  on  the  several  parts  of  the  plan  described  by  you  : 

1st.  To  go  to  the  Croton  watershed  for  the  additional  supply. 

Every  year  there  is  a  waste  of  water  from  the  water-shed  much 
greater  than  the  quantity  now  supplied  to  the  city. 

This  can  be  made  available,  to  a  great  extent,  by  additional 
storage  reservoirs  of  sufficient  capacity. 

The  alternative  is  to  divert  a  supply  from  the  Housatonic  river, 
by  means  of  a  canal  and  tunnel  into  the  Croton  valley,  estimated  to 
cost,  with  the  damages  to  the  mill  property  on  the  river,  about 
$2,500,000. 

The  canal  provided  for  in  the  estimate  I  consider  quite  insufficient 
to  provide  for  the  obstruction  to  the  flow  from  ice.  I  should  recom- 
mend it  to  be  made  of  much  greater  depth  than  proposed,  with 
walled  sides,  instead  of  earth  slopes,  for  at  least  part  of  the  depth. 
As  the  canal  would  be  about  30  miles  long,  this  would  add  largely 
to  the  cost.  I  also  consider  the  estimate  of  damages  to  the  mill 
property  much  too  low. 

The  Housatonic  river  being  in  another  State  would  be,  as  you 
suggest,  a  very  serious  objection. 


28 


Your  estimate  of  the  cost  of  sufficient  storage  on  the  Croton  river 
is  $4,000,000.  The  cost  of  the  Housatonic  plan,  in  my  judgment, 
would  not  be  very  much  less  than  this. 

There  being  no  great  saving  in  cost,  the  want  of  jurisdiction,  to 
my  mind,  points  decidedly  to  the  Croton  water-shed  as  being  the 
proper  source  of  supply. 

2d.  "  To  build  a  masonry  dam  on  the  bed  rock  near  Quaker 
"  bridge  on  the  Croton,  about  4^  miles  below  the  present  dam,  and 
"  thereby  raise  the  water  level  to  200  feet  above  tide." 

3d.  "  This  reservoir  thus  made,  to  contain  about  32,000,000,000 
"  gallons  of  storage  above  the  line  which  will  keep  water  11'  5"  deep 
"  in  an  aqueduct  12  feet  diameter." 

This  dam  would  be  nearly  200  feet  high  in  the  highest 
part,  and  would  be  a  work  of  great  magnitude,  but  I  think  entirely 
practicable,  and  as  it  would  include  a  larger  water-shed  than  reservoirs 
higher  up  the  river,  and  create  an  available  storage  capacity  of 
32,000,000,000  of  gallons  at  an  estimated  cost  of  $4,000,000,  or  at  the 
rate  of  $125  *  per  million  gallons,  it  would  appear  to  be  the  most 
economical  mode  of  obtaining  storage  in  the  Croton  water-shed. 

In  the  report  of  the  Commissioner  of  Public  Works  for  the  quarter 
ending  June  30,  1879,  "it  is  estimated  that  the  average  cost  per 
"  million  gallons,  of  all  the  reservoirs  projected  in  the  Croton  basin, 
"  will  be  $200." 

A  point  to  be  considered  in  a  reservoir  of  this  elevation  and 
magnitude,  is  the  probable  loss  from  percolation,  elsewhere  than  at 
the  dam  ;  the  geological  formation  appears  to  be  very  favorable  in 
this  respect,  but  I  think  there  would  be  some  loss.  I  should  expect, 
however,  that  the  additional  water-shed,  which  would  be  obtained  at 
the  proposed  site,  over  that  at  the  site  of  the  present  dam,  would 
fully  compensate  for  this  loss. 

4th.  "  To  run  the  aqueduct  from  the  dam  to  High  Bridge  as  far 
"  as  possible  in  tunnel,  and  to  avoid  embankments  -whenever 
"  possible." 

The  experience  with  the  present  Croton  aqueduct  is  so  clearly  and 
distinctly  in  favor  of  avoiding  embankments,  and  constructing  either 


*  This  includes  cost  of  dam  to  full  height. 


29 


in  tunnel  or  open  cutting,  that  I  do  not  see  that  anything  more  need 
be  said  on  that  point. 

5th.  "To  cross  the  Harlem  river  by  a  syphon,  either  tunnel 
"  through  rock  or  pipes  laid  on  river  bottom  ;  to  cross  Manhattan 
"  valley  by  a  similar  syphon,  and  to  build  the  rest  of  the  aqueduct 
"  between  High  Bridge  and  the  Central  Park  reservoir  in  tunnel 
"  wherever  possible." 

6th.  "  To  raise  the  gate-house  at  the  present  dam  to  suit  the  new 
"  water  level,  and  to  thoroughly  strengthen  the  present  aqueduct 
"  between  this  and  the  new  dam." 

7th.  "When  the  new  aqueduct  is  completed  to  rebuild  those 
' '  portions  of  the  present  structure  on  embankment  where  it  has  shown 
"  signs  of  weakness." 

I  am  not  sufficiently  familiar  with  the  localities  to  express  an 
opinion  on  all  these  points. 

Crossing  the  Harlem  river  by  a  high  bridge  I  think  should  be 
avoided  if  possible,  as  being  too  much  exposed  to  injury.  Either  of 
the  modes  you  suggest  would  be  far  better  in  this  respect,  and  I  have 
no  doubt  much  less  expensive. 

The  thorough  repair  of  the  present  aqueduct  as  soon  as  the  new- 
one  is  in  successful  operation,  is  no  more  than  ordinary  prudence 
would  require. 

Comparing  the  several  plans  to  which  you  have  called  my 
attention : 

New  aqueduct  on  the  Sawmill  river  route  with  a  new  dam  across 
the  Croton  river,  one-quarter  of  a  mile  above  the  head  of  Croton 
lake  ;  length  from  dam  to  High  Bridge  36.52  miles,  10.06  miles  being 
in  tunnel  ;  the  supply  to  be  derived  from  new  reservoirs  in  the  Croton 
basin  : 

Estimate  of  cost  of  conduit  and  pipe  work   $8,700,000  00 

Cost  of  32,000,000,000  gallons  of  storage  capacity  at 

$200   6,400,000  00 

$15,100,000  00 


3o 


New  aqueduct  on  the  Sawmill  river  route  with  new  dam  as  above  ; 
the  supply  to  be  derived  from  the  Housatonic  river  : 

Conduit  and  pipe  work  as  above   $8,700,000  00 

Estimate  of  cost  of  supply  from  the  Housatonic,  as  per 
report  of  the  Commissioner  of  Public  Works  for 
the  quarter  ending  June  30,  1879,  $2,500,000  ;  as 
stated  above  I  consider  this  too  low,  for  the 

present  purpose  say   $3,500,000  00 


$12,200,000  00 

By  the  plan  you  propose,  called  the  Quaker  bridge  plan,  the 
estimate  is  as  follows,  the  estimate  for  the  conduit  for  comparison 
with  the  other  plans,  being  for  a  capacity  of  1 50,000,000  of  gallons 
per  day,  'the  same  as  for  the  preceding,  requiring  a  conduit  of  not 
more  than  ten  feet  diameter  : 

Dam  and  land  damages  for  reservoir   $4,000,000  00 

27  miles  of  conduit   8,028,000  00 


$12,028,000  00 

In  view  of  the  great  objection  of  deriving  the  supply  from  a  source 
not  within  the  jurisdiction  of  the  State  of  New  York,  I  think  the  choice 
would  lay  between  the  two  plans  deriving  the  supply  from  the  Croton 
water-shed. 

By  the  above  estimates  the  cost  would  be  much  less  by  the  plan 
you  propose  than  by  the  Sawmill  river  plan,  and  I  see  no  advantage 
that  the  latter  plan  would  have  to  compensate  for  its  increased  cost  ; 
of  the  three  plans  considered  as  above,  I  have  no  hesitation  in  recom- 
mending the  Quaker  bridge  plan  as  being  the  most  advisable  one 
to  adopt. 

Very  respectfully, 

JAMES  B.  FRANCIS. 

Lowell,  Mass.,  December  30,  1881. 


31 


OPINION  OF  ROBERT  K.  MARTIN,  CHIEF  ENGINEER 
(NEW)  BALTIMORE  WATER  SUPPLY. 

Baltimore  Water  Department,  ) 
Chief  Engineer's  Office,  City  Hall,  V 

December  30,  1881.  ) 

Isaac  Newton,  Esq., 

Chief  Engineer,  Croton  Aqueduct : 

SlR — I  had  the  honor  to  receive  from  yon  a  communication,  dated 
December  14,  188 1,  containing  your  conclusions  upon  an  additional 
water  supply  for  New  York  City. 

Having  examined  the  maps,  plans,  profiles,  and  reports  relating  to 
the  matter,  and  after  having  made  a  personal  inspection  of  the  site  of 
the  proposed  dam  near  Quaker  bridge,  and  a  careful  study  of  the 
subject,  I  beg  leave  to  present  the  following  report : 

By  reference  to  a  "  table  showing  waste  of  water  over  the  Croton 
dam,"  it  will  be  seen  that  a  large  amount  of  water  annually  goes  to 
waste  in  the  Croton  water-shed. 

This  waste,  if  stored,  would  be  more  than  enough  for  your  present 
wants,  and  will  be  sufficient  in  the  future,  for  a  largely  increased 
consumption. 

Again,  the  Croton  water-shed  is  the  nearest  large  supply  to  your 
point  of  delivery. 

These  facts  influence  me  in  saying  that  the  most  available  source 
from  which  to  obtain  an  additional  water  supply  is  the  Croton  water- 
shed. 

In  order  to  store  the  water  of  the  Croton  water-shed,  you  propose 
building  a  masonry  dam  on  bed  rock  near  Quaker  bridge,  43^  miles 
below  the  present  Croton  dam,  and  thereby  raise  the  water-level  in 
the  Croton  basin  to  200  feet  above  tide,  which  will  give  a  storage 
capacity  of  about  32,000,000,000  gallons. 

In  my  opinion  a  dam  of  such  a  height  as  you  propose  should  be 
of  masonry  laid  in  hydraulic  mortar,  which,  in  the  hands  of  compe- 
tent engineers,  I  believe  to  be  entirely  practicable.  My  own  views 
are  fully  sustained  by  the  experience  of  French  engineers,  with 
similar  dams,  of  nearly  the  same  height. 

You  propose  to  build  an  aqueduct  from  the  dam  at  Quaker 
bridge  to  High  bridge,  as  far  as  possible  in  tunnel,  and  to  avoid 
embankments  wherever  possible. 


32 


An  aqueduct  is  the  main  artery  of  a  water  supply,  and  should  be 
located  where  it  will  be  safe  and  give  the  least  trouble  in  the  future. 

In  my  opinion,  the  best  location  for  an  aqueduct  is  in  tunnel, 
where  practicable. 

The  form  of  an  aqueduct  that  I  would  recommend  should  ^be 
circular,  the  diameter  sufficient  to  preclude  the  possibility  in  the 
future  of  wishing  that  it  had  been  larger. 

Harlem  river  and  Manhattan  valley  can  be  crossed  either  with  a 
tunnel  or  by  pipes,  laid  on  the  river  bottom,  or  beneath  the  surface. 

There  can  be  no  difficulty  in  the  raising  of  the  gate-house,  at  the 
present  Croton  dam,  to  suit  the  higher  water-level,  and  also  strengthen 
the  present  aqueduct  between  the  present  Croton  dam  and  the 
proposed  new  dam. 

After  your  new  aqueduct  is  completed,  you  can  rebuild  those 
portions  of  the  present  aqueduct,  or  embankment,  where  it  has  shown 
signs  of  weakness. 

I  consider  that  no  large  city  should  be  dependent  on  a  single 
aqueduct  for  its  water  supply. 

Your  plan  of  constructing  a  large  storage  supply  at  Quaker  bridge  is 
preferable  to  the  building  of  storage  reservoirs  in  the  upper  Croton  basin. 

These  storage  reservoirs,  in  the  upper  Croton  basin,  can  be 
availed  of  in  the  future,  when  the  storage  at  Quaker  bridge  becomes 
inadequate.  The  Housatonic  plan,  as  a  source  of  supply  in  place  of 
storage,  has  objections.  It  is  located  in  an  adjoining  State,  where  it 
will  be  difficult  to  exercise  control  over  pollutions,  or  enforce 
regulations. 

Furnishing  a  city  with  pure  water  through  an  open  canal,  at  all 
seasons  of  the  year,  and  guarding  every  avenue  of  pollution  along  its 
line,  is  a  serious  problem. 

Is  it  not  possible  that  the  Housatonic  will  be  subjected  to  the 
same  diminution  of  flow  as  the  Croton  during  a  drought,  and  may 
you  not,  eventually,  have  to  resort  to  storage,  to  keep  up  this  supply  ? 

After  a  careful  study  of  the  whole  subject,  I  feel  confident  that 
the  plan  recommended  by  you  is  not  only  advisable,  but  the  proper 
one  for  an  additional  supply  of  water  for  New  York  City. 
Respectfully  submitted, 

ROBERT  K.  MARTIN, 

Chief  Engineer. 


33 


"  A." 

REPORT  ON  SAW  MILL  RIVER  AND  BRONX  RIVER 

PLANS. 

Department  of  Public  Works,  ^ 
Engineer's  Office,  City  Hall,  > 
New  York  City,  January  3,  1876.  ) 

Hon.  Fitz  John  Porter,  Commissioner  of  Public  Works: 

Sir — In  compliance  with  your  instructions,  two  surveying  parties 
were  organized  under  Mr.  Charles  J.  Mc Alpine  and  Mr.  Horace 
Loomis,  to  ascertain  the  best  route  for  another  aqueduct  between  the 
Croton  river  and  the  Harlem  river,  at  High  bridge. 

These  parties  were  placed  under  the  charge  of  Mr.  Thomas  A. 
Emmett,  who  for  the  last  four  years  has  had  charge  of  the  reservoirs 
in  the  Croton  valley,  and  whose  report  of  the  surveys  and  the  esti- 
mated cost  of  the  new  aqueduct  is  hereto  annexed.  A  careful  examina- 
tion of  the  Croton  river  was  made,  showing  the  most  favorable  place 
for  another  dam  was  about  a  quarter  of  a  mile  above  the  head  of  the 
Croton  lake  and  just  below  the  mouth  of  the  Muscoot  river.  It  is  at 
this  point  proposed  to  raise  a  dam  30  feet  above  the  lip  of  the 
present  dam,  which  will  form  a  reservoir  and  settling  basin  covering 
about  800  acres,  and  will  be  about  seven  miles  in  length  and  hold 
about  1,180,000,000  gallons. 

Surveys  for  the  aqueduct  were  made  across  the  divide  to  the  head 
waters  of  the  Bronx,  and  down  that  valley,  and  also  further  to  the 
west  to  the  Pocantico  and  Sawmill  rivers. 

The  length  of  the  aqueduct  from  the  reservoir  to  the  High  bridge, 
on  the  Bronx  river  route,  will  be  36.08  miles,  and  by  the  Sawmill 
river  route  36.52  miles. 

The  aqueduct  will  start  from  the  Croton  river  with  an  elevation  of 
thirty  (30)  feet  above  the  present  aqueduct,  and  descend  on  a  grade 
of  12.67  inches  per  mile  to  the  vicinity  of  Jerome  Park,  at  which  point 
the  high  grounds  fall  away  so  far  as  to  render  the  continuance  of  the 
aqueduct  of  masonry  expensive  and  objectionable. 

It  is  here  proposed  to  construct  a  reservoir,  and  from  this  point 
carry  the  water  in  cast-iron  pipes.    The  water  in  the  reservoir  will 


3 


34 


stand  forty-two  (42)  feet  above  that  of  the  waters  in  the  reservoirs 
in  the  Central  Park. 

The  estimate  is  based  on  an  aqueduct  of  sufficient  capacity  to 
carry  1 50,000,000  gallons  per  day,  which,  with  the  present  aqueduct 
carrying  100,000,000  will  give  a  daily  supply  of  250,000,000  gallons. 

The  drainage  area  of  the  Croton  basin,  above  the  Croton  dam,  is 
338  square  miles. 

In  the  report  of  the  Croton  Aqueduct  Board,  made  to  the  Com- 
mon Council  in  1863,  they  estimate  the  daily  flow  of  the  Croton  river 
at  338,832,128  gallons. 

Mr.  Tracy,  late  Chief  Engineer  of  the  Croton  Aqueduct,  in  his 
report  in  May,  1873,  says:  "For  many  years  past  the  Department 
has  kept  a  gauge  of  the  daily  quantity  of  water  flowing  over  the 
Croton  dam,  in  addition  to  that  which  is  conveyed  to  the  city  by  the 
aqueduct,  and  during  the  past  ten  years  an  average  daily  quantity  of 
340,000,000  gallons  has  run  to  waste  over  the  dam,  in  addition  to  the 
quantity  that  was  brought  to  the  city." 

Professor  Chandler,  President  of  the  Board  of  Health,  who  has 
made  the  Croton  a  special  study,  says  of  it  :  "  We  have  an  available 
supply  of  387,000,000  gallons."  Of  the  purity  of  the  Croton  water,  he 
says:  "The  character  of  the  Croton  water-shed  is  of  a  nature  to 
"  guarantee  water  of  the  best  quality.  Mountains  and  hills  of  Lau- 
"  rentian  gneiss  receive  the  rain-fall,  which  is  quickly  absorbed  and 
"  filteredby  the  pure  siliceous  sands  and  gravels,  to  gush  out  in 
"  numberless  springs,  feeding  the  brooks  which  bear  the  sparkling 
"  waters  to  the  ponds  and  reservoirs.  From  these  flow  the  large 
"  streams  which  by  uniting  form  the  Croton  river.  This  is  finally 
"  expanded  by  the  dam  at  the  head  of  the  aqueduct,  into  a  broad, 
"  deep  lake,  the  fountain  reservoir,  or  Croton  lake,  in  which  the 
"  quiet  waters  deposit  the  finer  sediments  and  thus  undergo  a  final 
"  purification  before  they  are  admitted  to  the  aqueduct.  Nowhere 
"  along  the  streams  can  anything  be  found  which  can  render  the 
"  waters  impure.  Rugged  rocks  or  bright  green  pastures  generally 
"  border  them.  At  certain  seasons  of  the  pear,  as  when  the  snows 
"  melt  in  the  spring,  and  the  waters  scour  the  still  frozen  earth,  the 
"  water  is  often  discolored  when  it  reaches  the  city,  and  alarmists 
"  begin  to  discuss  the  danger  to  be  apprehended  from  the  poisons 


35 

"  and  miasmata  which  are  derived  from  the  bogs  and  morasses  of 
"  Westchester  County  and  Putnam  County.  But  we  have  never 
"  keen  able  to  trace  any  sickness  whatever  to  such  sources,  and  do 
"  not  believe  that  any  unwholesome  impurities  ever  occur  in  our 
"  water.    The  purity  of  the  Croton  water  is  remarkable."  * 

The  present  aqueduct  is  now  bringing  into  the  city  daily  all  the 
water  that  it  can  carry  with  safety,  and  it  is  necessary  that  steps  be 
taken  at  once  to  bring  in  an  additional  supply. 

The  importance  of  a  full  supply  is  too  great  to  be  dependent  upon 
one  aqueduct,  and  another  should  be  built  entirely  away  from  and 
independent  of  the  present,  that  in  case  of  accident  to  one  the  other 
may  not  be  affected  by  it.  It  is  now  impossible  to  keep  the  water  out 
of  the  present  aqueduct  sufficient  time  to  make  the  thorough  repairs  to 
it  that  it  requires.  Had  we  another  aqueduct,  the  water  could  be 
drawn  from  it  for  such  time  as  may  be  necessary  to  thoroughly  repair 
it,  when  it  could  be  made  fully  as  good  as  when  the  Croton  water 
was  first  brought  through  it  in  1842. 

In  order  to  keep  the  supply  necessary  for  the  city  until  another 
aqueduct  is  built,  meters  will  be  required  on  all  places  where  extra 
water  is  used  to  stop  the  waste,  and  every  effort  made  to  stop  the 
waste  in  private  houses.  By  such  exertions  the  demand  may  be  kept 
down  to  the  present  supply  until  such  a  time  as  another  aqueduct  can 
be  built.  Work  on  the  present  aqueduct  was  commenced  in  the  fall 
of  1837,  and  the  water  brought  through  it  and  let  into  the  reservoirs 
at  Eighty-sixth  street,  in  July,  1842. 

The  present  facilities  for  excavating  rock  with  steam  drills  will 
expedite  work,  but  it  will  not  be  safe  to  expect  the  completion  of  the 
work  and  passage  of  water  through  it  in  less  than  three  years  after  the 
work  shall  be  placed  under  contract. 

The  quantities  of  work  in  the  estimate  for  the  new  aqueduct  are 
full  and  the  prices  such  as  the  work  can  be  done  for. 

Very  respectfully,  your  obedient  servant, 

JOHN  C.  CAMPBELL, 

Chief  Engineer. 


*"From  Report  of  Croton  Aqueduct  Board,  1863. 


36 


Department  of  Puplic  Works, 
Engineer's  Office,  Carmel,  Putnam  County, 
New  York,  December  20,  1875. 

John  C.  Campbell,  Esq.,  Chief  Engineer : 

Sir — I  herewith  submit  a  report  of  operations  in  the  field  (together 
with  profile  and  estimates)  of  the  engineering  parties  who  have  been 
engaged  in  making  surveys  for  a  new  aqueduct  from  the  Croton  to 
the  Harlem  river.  The  map  is  not  quite  completed,  but  will  be  sent 
to  you  in  a  few  days. 

The  first  party,  under  the  charge  of  Mr.  Charles  L.  McAlpine, 
began  work  on  the  20th  of  August,  locating  the  site  for  a  dam  across 
the  Croton  river  one-quarter  of  a  mile  above  the  head  of  Croton  lake, 
and  establishing  a  flow-line  for  a  new  lake  or  settling  basin  30  feet 
higher  than  the  lip  of  the  present  Croton  dam.  From  the  point 
where  the  dam  was  located  a  line  was  run  down  the  east  bank  of  the 
Croton  lake  on  a  descending  grade  of  0.020  per  100  feet,  or  1  56-100 
feet  per  mile,  which  grade  was  continued  to  the  end  of  the  line. 
Leaving  Croton  Lake  at  the  mouth  of  the  Kisco  river,  the  line  follows 
up  that  stream  to  the  summit  between  it  and  the  Bronx  river,  and 
down  the  Bronx  to  the  end  of  the  route.  The  length  of  this  route  to 
High  Bridge  is  36  8-100  miles,  of  which  13  98-100  miles  is  tunnel,  19 
9-100  miles  in  open  cuts  and  embankments,  and  3  1-100  miles  in  cast- 
iron  pipes  to  the  High  bridge  over  the  Harlem  river. 

The  second  party,  under  the  charge  of  Mr.  Horace  Loomis,  began 
on  the  6th  of  September,  at  a  point  on  Mr.  McAlpine'-s  line  on  the 
north  bank  of  Kisco  river,  near  its  mouth,  and  crossing  that  river 
continued  down  Croton  lake  to  a  small  stream  called  Trout  or  Van 
Cortland  brook,  and  followed  it  to  the  summit  or  head  waters  of  the 
Pocantico  river  ;  following  down  that  stream  four  and  a  half  miles, 
and  thence  across  to  Sawmill  river  valley,  which  was  followed  for 
twelve  and  a  quarter  miles,  thence  crossing  the  ridge  to  the  valley  of 
Tibbet's  brook.  In  the  valley  of  Tibbet's  brook  the  line  runs  about 
three  miles  alongside  of  the  present  aqueduct,  varying  in  distance 
from  fifty  to  one  hundred  feet  to  the  east  of  it,  and  on  ground  from 
thirty  to  forty  feet  higher.  From  where  it  leaves  the  aqueduct  the 
line  runs  west  of  Woodlawn  Cemetery  and  thence  on  high  ground  to 
its  junction  with  Mr.  McAlpine's  line.    The  length  of  this  route  from 


37 


the  dam  at  High  bridge  is  36  52-100  miles,  of  which  106-100  miles  is 
tunnel,  23  45-100  miles  is  open  cuts  and  embankments,  and  3  1-100 
miles  in  pipes. 

For  the  lake  above  the  dam  two  flow-lines  were  run,  one  of  them 
thirty  feet  and  the  other  twenty-five  feet  above  the  lip  of  Croton  dam. 
The  area  of  land  covered  by  the  upper  flow-line  will  be  860  acres,  and 
the  capacity  is  estimated  at  1 , 180, 000,000  of  gallons.  The  lower  flow- 
line  will  cover  an  area  of  614  acres,  and  will  contain  about  765,000,000 
of  gallons.  The  upper  flow-line  covers  the  track  of  the  Lake  Mahopac 
branch  of  the  Harlem  Railroad,  from  one  to  six  feet  in  depth,  for  a 
distance  of  1,300  feet,  and  the  lower  flow-line  for  a  distance  of  400 
feet  nearly  touches  the  track,  the  deepest  place  being  one  foot.  The 
water  by  the  upper  flow-line  will  also  cover  about  four  feet  above  the 
lower  chord  of  the  railroad  bridge  across  the  Croton  river,  the  track 
being  laid  on  the  upper  one. 

Two  points  were  examined  for  receiving  reservoirs  in  the  vicinity 
of  Jerome  Park,  one  containing  65  acres,  with  a  capacity  of  about 
600,000,000  of  gallons,  the  other  containing  about  60  acres,  with  a 
capacity  of  about  550,000,000  of  gallons. 

In  making  these  surveys  the  country  has  been  carefully  examined, 
and  lines  run  through  every  gap  or  opening  that  was  found  between 
the  Bronx  river  and  Pocantico  river  and  the  Bronx  river  line,  which 
runs  from  the  summit  along  the  head  waters  of  Sawmill  river  to 
Unionville,  is  connected  with  the  Sawmill  river  line  a  short  distance 
below  that  place.  In  crossing  Sprain  Brook,  on  the  Bronx  river 
route,  the  estimate  is  for  carrying  the  water  across  that  valley  in  cast- 
iron  pipes.   The  inside  area  of  the  proposed  aqueduct  is  75  32-100  feet. 

Estimates  are  made  on  the  Bronx  river  and  Sawmill  river  routes 
as  being  the  most  direct  and  presenting  the  fewest  obstacles  to  the 
construction  of  an  aqueduct,  and  I  think  the  estimates  annexed  to 
this  report  will  fully  cover  the  cost. 

I  am  indebted  to  Messrs.  McAlpine  and  Loomis,  and  the  young 
men  under  them,  for  their  careful  and  skillful  prosecution  of  the 
surveys,  and  their  promptness  and  dispatch  in  making  up  the 
estimates  and  profiles. 

Respectfully  submitted, 

THOMAS  A.  EMMETT, 

Assistant  Engineer  in  Charge. 


38 


ESTIMATES  ON  SAW  MILL  AND  BRONX  RIVER  PLANS 
ACCOMPANYING  ABOVE  REPORT. 

Estimate  for  Lake  and  Dam  at  head  of  New  Aqueduct. 


860  acres  of  land,  including  buildings   $3CO,oco  00 

Clearing  and  grubbing  -   5,ooo  00 

8,500  cubic  yards  of  earth  excavation,  at  25c   2,125  00 

24,000          "          rock  excavation,  at  $1.25   30,00000 

2,coo          "          tunnel  cutting  in  rock,  at  $6   12,000  00 

90,000          "          embankment,  at  50c   45,000  00 

500          "          concrete  masonry,  at  $6   3>ooo  00 

4,500          "          rubble  masonry,  at  $5   22,500  00 

200          "          brick  masonry,  at  $12   2,400  00 

2,000          "          cut-stone  masonry,  at  $25   50,000  00 

Gate -houses,  gates,  screens,  etc   30,000  00 

Making  new  road,  raising  railroad  bank,  and  bridge   30,000  00 


$532,025  00 


Estimate  for  New  Aqueduct  on  Saw  Mill  River  route,  from  Dam  to  High  Bridge  36  52-100 
miles,  of  which  10  06-100  miles  is  in  Tunnel,  23  45-100  miles  in  Open  Cut,  etc.,  and 


3  01 -100  miles  by  Fipes. 

300  acres  of  land  for  right  of  way,  at  $500   $150,000  00 

Clearing  and  grubbing   5, 000  00 

66o,coo  cubic  yards  of  earth  excavation,  at  30c   198,000  00 

130,000          "          rock  excavation,  at  $1.50   195,000  00 

254,000          "          tunnel  cutting  in  rock,  at  $6   1,524,000  00 

200,000          "          embankment,  at  30c   6o,oco  00 

75, coo          "          foundation  wall,  at  $2.25   168,75000 

65,000          "          protection  wall,  at  $2.25   146,250  00 

41,000          '•          concrete  masonry,  at  $6   246,000  00 

253,400          "          rubble  masonry,  at  $6   1,520,40000 

130,300          "          brick  masonry,  at  $10   1,303,000  00 

6,750          4<          hammer-dressed  masonry,  at  $15   101,250  00 

3  miles  of  new  roads   30,000  00 


$5,645,650  00 

3  01-100  miles  of  48-inch  pipes  (six  lines),  at  $132  per  foot   2,097,850  00 

Gate-house   30,000  00 

Estimate  of  dam   532,025  00 

60  acres  of  land,  at  $2,000  per  acre   $120,000  00 


350,000  cubic  yards  of  earth  excavation,  at  25c   87,500  00 

105,000          "          rock  excavation,  at  $1.25   131,25000 

120,000           "          embankment,  at  30c   36,000  00 

12,000          "          puddle,  at  $1   12,000  00 


39 


6,000  cubic  yards  of  slope  wall,  at  $2   $12,000  00 

Gate -houses,  gates,  etc   50,000  00 

 $448,750  00 


$8,754,275  00 

Add  for  superintendence  and  contingencies   457,714  00 


$9,191,989  00 


Estimate  for  New  Aqueduct  on  Bro?ix  River  Route,  from  Dam  to  High  Bridge,  3608-100 
miles,  oj w 'hick  13  98-100  miles  is  in  Tunnel,  19  09100  miles  in  Open  Cuts,  etc.,  and 


3  01- 100  miles  by  Pipes. 

300  acres  of  land  for  right  of  way,  at  $500    $150,000  00 

Clearing  and  grubbing   5,000  co 

350,000  cubic  yards  of  earth  excavation,  at  30c   105,000  00 

230,000          "          rock  excavation,  $1.50   345,000  00 

360,000          "          tunnel  cutting  in  rock,  at  $6   2,160,000  00 

100,000          "          embankment,  at  30c   30,000  00 

55,000          "          foundation  wall,  at  $2.25   123,75000 

50,000          "          protection  wall,  at  $2.25   112,50000 

28,000          '•          concrete  masonry,  at  $6   168,000  00 

203,400          "          rubble  masonry,  at  $6   1,220,400  00 

113,300          "          brick  masonry,  at  $11   1,246,30000 

8,000          "          hammer-dressed  masonry,  at  $15   120,00000 

2  gate-houses,  etc.,  at  Sprain  brook   40,000  00 

18,000  lineal  feet  of  48-inch  pipe,  at  $22   396,000  00 


$6,241,950  00 

3  01-100  miles  of  48-inch  pipes  (6  lines),  at  $132  per  foot   2,097,850  00 

Gate -house   30,000  00 

Estimate  of  dam   532,025  00 

Reservoir  near  Jerome  Park. 

60  acres  of  land,  at  $2,000  per  acre   $120,000  00 

350,000  cubic  yards  of  earth  excavation,  at  25c   87,500  00 

105,000  "  rock  excavation,  at  $1.25   131,25000 

120,000  "  embankment,  at  30c   36,000  00 

12,000  "  puddle,  at  $1   12,000  00 

6,000  "  slope  wall,  at  $2   12,000  00 

Gate -houses,  gates,  etc   50,000  00 

  448,750  00 

#9>35°>575  °o 

Add  for  superintendence  and  contingencies   467,529  00 


$9,818,104  00 


4Q 


EXTRACT  FROM  REPORT  OF  THE  CROTON  AQUEDUCT  BOARD,  MADE 
JANUARY  5,   1863,  TO  THE  COMMON  COUNCIL. 

With  an  aggregate  annual  precipitation  of  rain  and  snow  of  42 
inches  vertical  height,  which  is  about  the  average  for  many  years 
past,  the  quantity  falling  upon  the  Croton  basin,  tributary  to  our 
works,  is  equal  to  an  average  of  667,674,257  gallons  per  day. 

Judging  from  experiments  made  in  other  localities,  the  physical 
and  geological  features  of  which,  while  resembling  the  Croton  basin 
to  some  degree,  are  less  favorable  as  a  whole,  the  loss  from  evapora- 
tion, vegetation,  and  such  absorption  as  does  not  subsequently 
reappear  in  springs,  may  be  put  down  as  equal  to  14  inches  vertical 
height  of  the  total  annual  rain-fall.  Make  a  further  deduction  equiva- 
lent to  one-sixth  of  the  entire  annual  rain-fall,  to  cover  loss  by  evapo- 
ration and  filtration  from  storage  reservoirs,  and  we  find  that  a 
quantity  equal  to  an  average  of  338,832,128  gallons  per  day,  would 
find  its  way  to  Croton  dam  and  the  inlet  of  our  aqueduct. 

Were  it  necessary  to  use  the  entire  yield  of  the  Croton  basin,  a 
great  portion,  if  not  the  whole  of  this  quantity,  could,  by  a  proper 
system  of  storage  reservoirs,  be  saved  and  made  available. 


4i 


B." 


Estimate  of  Mr.  G.  W.  Birdsall,  First  Assistant  Engineer,  for  con- 
veying water  from  termination  of  surveys  of  Saw-mill  and  Bronx 
river  routes,  north  side  of  High  Bridge,  to  Central  Park  Reservoirs. 

Estimated  Cost  of  Laying  10-48"  Pipe  from  North  End  of  High  Bridge  to  Connections  with 

Central  Park  Reservoirs. 


From  north  end  High  Bridge,  by  Sedgwick 
and  Ogden  avenues,  to  McComb's  Dam, 
4,800  feet  

Across  Harlem  river  to  One  Hundred  and 
Fifty-third  street,  1,500  feet  

McComb's  Dam  road  and  One  Hundred  and 
Fifty -third  street,  and  Eighth  avenue  to 
North  Gate-house,  Central  Park,  5  pipe, 
16,000  feet  

Seventh  avenue  and  One  Hundred  and  Fifty  - 
third  street  to  Fifth  avenue  and  One 
Hundredth  street  and  North  Gate-house, 
Central  Park,  5  pipe,  18,000  feet  

Total  lineal  feet  

82,000  tons  48"  pipe  delivered  at  dock,  at  $30. 

350  tons  specials  and  branches,  at  $75  

Stop-cocks,  hydrants,  etc  

Hauling  and  laying  235,000  ft.  48"  pipe,  at  $2. 

60,000  cubic  yards  rock  excavation,  at  $2.50. 

235,000         "        earth  excavation,  at  30  c . 

290,000         "        filling,  at  10  c  

80,000  square  yards  pavement  to  relay,  at  25  c. 

Extra  expense  crossing  Harlem  river — 

6,000  cubic  yards  concrete,  at  $10  

30,020         "        excavation,  at  $5  

Contingencies  


Lineal  Feet. 

48,000 
15,000 

8o,000 

90,000 


233,000 


Add  10  per  cent  for  engineering  and 
contingencies  


$2,460,000  00 
26,250  00 
71,000  CO 
470,000  00 
150,000  CO 
70,500  00 
29,000  00 
20,000  00 


$3»546,75°  00 
354,675  00 

$3,901,425  00 


42 


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54 


FROM  REPORT  OF  DR.  DANIEL  DRAPER,  1876. 

THE  DROUGHT  OF  1 876. 

The  most  important  meteorological  phenomenon  for  the  past  year 
was  the  drought  that  caused  great  scarcity  of  Croton  water  in  this 
city.  It  began  with  an  unusually  small  fall  of  rain,  the  total  amount 
for  January  being  .94  inch,  while  the  average  for  forty-one  years  is 
3.30  inches.  There  are  only  two  other  years  on  record  in  which  the 
rain-fall  for  that  month  was  less  ;  they  are  1839,  when  it  was  .69  inch, 
and  1849,  when  it  was  .61  inch.  The  following  two  months  were 
above  their  averages,  February  having  4.81  inches,  its  average  for 
forty-one  years  being  3.40  inches,  while  in  March  it  was  8.79  inches, 
the  average  being  3.76.  After  this  all  the  other  months  were  below 
their  averages,  except  September,  which  was  1.60  above,  as  is  shown 
in  Table  7. 


55 


TABLE  7. 

Table  showing  Monthly  and  Annual  Fall  of  Water  for  46 years,  in  the  Vicinity  of  New  York 
City  {at  Fort  Columbus,  Deaf  and  Dumb  Asylum,  and  New  York  Observatory,  Central  Park). 

Inches. 


Year. 

Jan. 

Feb. 

Mar. 

April 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Annual 
Amount. 

1836  

1 .09 

2.01 

2 .66 

0.63 

6.46 

1.44 

2-37 

3-4° 

2.00 

1 .90 

2.30  j 

27.57 

i837  

2.70 

3-7° 

8.20 

7-5o 

9-5o 

8.50 

5-9° 

6.30 

2. 10 

2. 11 

2.90 

6.10 

65-51 

1838  

3-93 

3.70 

4.10 

2.50 

3-99 

312  J 

1.83 

4-79 

4.96 

3-64 

3- 10 

2.24  1 

41.90 

1839  

0.09 

2.05 

2.40 

3-35 

8 -37 

4-94 

i-35 

4.92 

3-59 

i-45 

2. 19 

7  .01 

42.97 

_  ft 

1 . 04 

1 . 04 

2 . 92 

2.03 

2-39 

2 . 40 

1 . 80 

4-25 

1 . 84 

4-59 

2.90 

1 .00 

29.80 

1841  

5-3° 

0 

0. 00 

2-35 

3-93 

3-95 

4-65 

4.90 

2.50 

2.90 

4.40 

3-7° 

2.70 

42.08 

1842  

1 .07 

0  _ 
2.85 

1-25  , 

3.60 

3. 6o 

3-3° 

3.80 

_  0 

2  .01 

2. 10 

4-3° 

1.80 

3-50 

33-98 

-a 
u 

1843  

1 .00 

2.31 

2.13 

2.14 

1 .00 

O.76 

1 .64 

15.26 

3.06 

5-91 

2.82 

3-34 

41-37 

c 

1844  

2.00 

1.03 

4-5° 

O.S5 

3-41 

2-37 

6.00 

2.73 

4-5° 

4.08 

i-73 

2.82 

36-38 

06  ] 

1845  

4.87 

3.22 

3-33 

T  .  22 

i-75 

3-7° 

i-75 

3-21 

2.62 

2.50 

3-4° 

2.51 

34.08 

1846  

3-92 

3.01 

3.82 

4.OI 

9.70 

i-39 

6.01 

n  0 

3.88 

0 

0.40 

i-34 

8.36 

2.99 

48.91 

< 

1847  

4 . 02 

5-74 

Q     .  Q 
O  .40 

1-53 

2 . 10 

6.7O 

1 .62 

6-93 

12.20 

2.13 

6.29 

6-35 

64.85 

1848  

i-75 

I  .00 

2  .  23 

I  .  IO 

7  .  20 

4-56 

2.64 

1. 41 

1.87 

6. 01 

i-59 

4.02 

36.80 

1849  

0. 01 

2.20 

0 

4.87 

O.C2 

3-47 

0.78 

1.43 

4-63 

i-55 

S-63 

1 .88 

4.01 

3*-74 

l850  

5-57 

2.04 

4.64 

2.72 

9. 20 

3-07 

3-92 

7.21 

4.71 

3.16 

2-33 

5-36 

54-53 

185I  

1 . 40 

4- 50 

1 . 70 

6.94 

4-73 

0.90 

4.72 

3-47 

1 .20 

2-95 

4-53 

3-72 

40.88 

2.92 

3.08 

4-43 

4-74 

2.24 

2. 11 

3-25 

6.20 

2.29 

2.06 

6.07 

4-45 

43-84 

1853  

4.14 

4.98 

2.03 

3-32 

ft 

5.80 

0 

4. 80 

4.40 

5-5° 

5-49 

3-9° 

6.80 

1 .04 

52.20 

■l854 

2.O0 

4.00 

0.70 

8 .  bo 

7.70 

2 . 20 

1 .90 

1.03 

1.90 

1.80 

3-95 

8.60 

45.18 

l855  

4-77 

5.12 

2.83 

2  .  00 

4.90 

5-83 

5.06 

2.90 

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7-37 

3.00 

6.86 

53-oi 

1856  

3-98 

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2 .  OO 

2  .  72 

O 

4.78 

3-58 

2.79 

6-73 

5-°5 

1. 18 

2.50 

4-45 

40.50 

1857  

4.99 

I.69 

2.32 

9-°5 

O.72 

5-43 

6.13 

3-9° 

4. 26 

1 .67 

1.30 

6.42 

53.88 

1858  

3.  Bo 

3-3° 

I.47 

4.83 

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6.42 

4-32 

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3-5° 

4.19 

5-99 

4.90 

51-87 

1859 

p    -7  P. 

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0.21 

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4.00 

4.76 

4.12 

6-45 

i-75 

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55-72 

c 
— 
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2.52 

3.28 

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4-54 

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3-33 

3-85 

6.24 

3-55 

7-57 

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5.62 

6.03 

4.24 

2.89 

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53-97 

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1863  

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7.04 

5-77 

5-69 

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8.32 

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4.81 

8.79 

3.06 

3-°3 

2.66 

3-65 

2.28 

5-28 

1 .42 

3-3i 

2-54 

41-77 

U 

1877  

2.62 

1.24 

5-56 

2.73 

0-95 

2.80 

5-73 

2.77 

i-33 

8.14 

5-63 

0.68 

40. 18 

1878  . . 

4.46 

3-75 

3-27 

1.97 

3.19 

3.08 

4.62 

7-97 

4.05 

2.43 

4-73 

5-i4 

48.66 

1879  

2.63 

2 .02 

3-4i 

4-33 

2.02 

3-i5 

3-58 

7-95 

2-37 

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2.20 

4.94 

39 -°3 

1880  

2.02 

2 . 12 

4.66 

2.90 

.62 

1. 14 

8-53 

5.26 

I.85 

2.81 

2.46 

2 . 27 

36.64 

1881 

4.80 

4-93 

5.8i 

0.95 

3.20 

5-35 

1.25 

.86 

•97 

1 .60 

2.36 

4.18 

36.26 

56 


This  drought  has  led  me  to  examine  the  following  question : 

Has  there  been  in  late  years  any  change  in  the  rain-fall  of  New 
York  City  or  its  vicinity  to  affect  seriously  its  zvater  supply  ? 

In  a  former  report  I  discussed  a  question  nearly  related  to  this, 
viz.  :  "  Does  the  clearing  of  land  increase  or  diminish  the  fall  of  rain." 
We  found  that  the  wide-spread  impression  that  the  clearing  of  land 
diminishes  the  volume  of  rain  is  not  based  on  fact.  We  shall  have 
to  study  the  present  question  in  a  similar  manner,  relying  on  the 
observations  then  used,  and  others  that  have  since  been  collected. 

As  the  water  supply  of  New  York  comes  from  the  Croton  river, 
we  shall  have  to  examine  the  table  of  the  rain-fall  on  the  shed  of  that 
river,  but  as  the  observations  for  it  extend  back  only  a  few  years,  it 
becomes  necessary  to  compare  them  with  those  of  New  York  City. 

The  annual  observations  at  Boyd's  Corners,  which  is  within  the 
Croton  water-shed,  are  from  1870  to  1877,  and  those  of  this 
Observatory  are  for  the  same  period.  By  the  table  it  appears  that  the 
rain-fall  of  these  stations  varies  from  year  to  year,  but  in  the  means 
for  the  series  there  is  a  variation  of  only  1.8  inch.  This  might  be 
expected  from  topographical  and  other  considerations. 


Years. 

1871. 

1872. 

1873. 

1874. 

1875. 

1876. 

Mean. 

Boyd's  Corners. . . . 

48.94 

40.74 

43-87 

42-37 

43.66 

40.68 

43-37 

51.26 

42.49 

47-99 

45-83 

40.90 

4x-77 

45-17 

The  fall  at  Boyd's  Corners  resembles  that  of  the  city.  We  may 
therefore  use  our  city  observations  for  the  missing  ones  there. 

The  fall  in  New  York  City  bears,  in  like  manner,  a  general 
resemblance  to  that  of  other  adjacent  cities,  as  Washington,  Phila- 
delphia, Providence  ;  and  since  there  exist  very  old  observations 
made  in  those  places,  they  may  be  used  in  investigating  the  rain-falls 
here.  Of  course  it  will  be  understood  that  I  am  not  here  speaking  of 
the  absolute  rain-falls  in  those  places,  but  the  variations  they  exhibit, 
and  using  those  variations  as  a  guide  to  the  determination  in  New 
York. 


57 


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6i 


TABLE  10. 

Storage  Drawn  in  1880  and  1881,  in  Million  Gallons. 


January. 

February.  1 

March. 

April. 

May. 

June. 

July. 

August. 

September. 

October. 

November 

December. 

1881. 

1881. 

1880. 

1880. 

1881. 

1880. 

1881. 

1880. 

1881. 

1880. 

1881. 

1880. 

1880. 

I  

60 

10 

75 

20 

5o 

90 

85 

90 

2  

50 

10 

75 

3° 

5o 

20 

90 

85 

90 

3  

So 

10 

75 

50 

50 

60 

90 

80 

90 

4  

50 

3° 

75 

60 

5o 

80 

90 

80 

70 

5  

50 

3° 

45 

75 

So 

80 

90 

80 

60 

6  

3° 

3° 

15 

75 

60 

80 

90 

80 

70 

7  

3° 

35 

2b 

75 

30 

85 

90 

80 

70 

8  

3° 

3° 

3b 

75 

3° 

85 

90 

80 

70 

9  

30 

30  .. 

65 

75 

30 

85 

90 

80 

70 

10  

30 

10 

70 

75 

60 

80 

90 

80 

70 

11  

30 

85 

75 

60 

20 

90 

75 

70 

12  

3° 

10 

85 

75 

70 

25 

90 

75 

90 

13  

10 

65 

60 

80 

25 

90 

75 

90 

14  

3° 

35 

60 

80 

25 

90 

75 

90 

15  

30 

65 

60 

90 

25 

90 

75 

90 

16  

40 

65 

45 

90 

25 

90 

75 

90 

17  

45 

45 

40 

90 

15 

90 

70 

90 

18  

45 

15 

70 

90 

35 

90 

70 

90 

19  

45 

15 

75 

90 

35 

90 

70 

90 

20  

45 

25 

30 

85 

90 

65 

90 

70 

90 

15 

21  

45 

30 

40 

85 

90 

60 

90 

70 

90 

15 

22  

80 

20 

40 

85 

90 

80 

90 

70 

90 

25 

23  

80 

20 

60 

85 

90 

85 

90 

70 

90 

25 

24  

65 

20 

60 

70 

90 

85 

90 

70 

90 

25 

25  

65 

50 

70 

90 

80 

90 

75 

90 

3° 

26  

65 

50 

70 

80 

80 

90 

75 

70 

3° 

27  

65 

3° 

50 

80 

80 

90 

70 

70 

30 

28  

75 

30 

60 

90 

85 

90 

70 

70 

20 

30 

29  

75 

40 

75 

90 

85 

90 

70 

60 

20 

3° 

3°  

40 

75 

90 

85 

90 

70 

60 

20 

40 

3i  

50 

10 

90 

70 

20 

40 

Total,  1880  

•••••• 

..  8,5 

20,000,003  gallons. 

I  JL&M  % 


of 


62 


TABLE  11. 

Existing  Storage — Artificial  and  Natural. 
(From  Report  of  August  12,  1879.) 

The  reservoirs  and  lakes  within  the  Croton  basin,  and  now 
available  for  storage  purposes,  are  as  follows  : 


Boyd's  Corners  Reservoir  , 

Middle  Branch  Reservoir   .  i^TfTtJ.  /.  4. . .  .  /.Cr$y 

Lake  Mahopac  .     , 

Lake  Kirk  

Lake  Gleneida  

Lake  Gilead  

Lake  Waccabuc  

Lake  Tonetta  

Barrett's  Pond  

China  Pond  

White  Pond  

Pine  Pond  '.  

Long  Pond  

Peach  Pond  

Cross  Pond  

Haine's  Pond  , 


Total  Gallons. 


Gallons. 
2,727,CC0,0OO 

4,004,000,000 

575,000,000 

565,000,000 

165,000,000 

380,000,000 

200,000,000 

50,000,000 

170,000,000 

105,000,000 

100,000,000 

75,000,000 
60,000,000 
230,000,000 
110,000,000 
25,000,000 


9,541,000,000 


TABLE  12. 


(From  Report  of  August  12,  1879.) 

The  following  table,  prepared  from  daily  observations  for  several 
years  by  the  Engineers  of  the  Croton  Bureau,  shows  the  rain-fall  and 
the  average  daily  quantity  of  water  running  in  the  Croton  river  : 


/0  (t3*> 


Year. 

Rainfall  at 
Boyd  s  Corners 
Reservoir. 

Average  Daily  Flow 
of  the  Croton  River  at 
Croton  Dam. 

Percentage  of 
Rain-fall  Running 
in  the  Stream. 

Inches. 

Gallons. 

Per  cent. 

1866  

51-77 

440,705,558 

1867  

50  -77 

541,318,397 

65  f 

1868  

50  -33 

600,524,194 

74- 

1869  

48.36 

456,575»&H 

58.  «~ 

1870  

4463 

347>935>3i8 

47  -  '  - 

1871  

48.94 

357,175,341 

45-  -  - 

1872  

40.74 

307,208,408 

49- 

1873  

43  87 

444,236,877 

67.  J- 

1874  

42.37 

427,638,306 

63.  > 

1875  

43.66 

425,021,738 

59-  *" 

1876  

40.68 

367,872,936 

56.  +  - 

1877  

46.03 

346,503,178 

45-  - 

1878  

54- 14 

462,854,308 

52. 

» 


r 


« 

f 


